Backport of cozystack#4254 to release-1.6.

Cluster-wide migration settings could only be applied by patching the KubeVirt
CR: the kubevirt chart did not render `migrations`, and the platform bundle did
not forward it. The optional `kubevirt.migrations` platform value now passes
through the generated Package to `spec.configuration.migrations`, and a hand
patch of that Package is undone on the next platform render, so this hop is the
only supported setter.

Four differences from main, all from release-1.6 predating the
disabledFeatureGates work:

- platform values gains a `kubevirt` block holding `migrations` alone, and the
  iaas bundle gains only the migrations hop;
- the wiring test takes the four migrations cases and the case for a null
  `kubevirt` block, without the assertions that belong to disabledFeatureGates
  cases absent here;
- update_idempotency_test.sh gains `run_update_logged`, which arrived on main
  alongside that work and the new cases need;
- the kubevirt Makefile header counts six sed patches rather than five.

Verified on this branch: 9 kubevirt chart tests, 31 platform wiring tests (102
across the platform suite), and update_idempotency_test PASS under GNU make and
sed. Removing the new awk guard from the Makefile turns that test red naming the
migrations block, so the ported guard is not decorative. On this line
(.Values.kubevirt).migrations is the only reader of .Values.kubevirt, and
rewriting it as .Values.kubevirt.migrations turns the null-block case red with a
nil pointer.

The automated backport in cozystack#4322 stopped with conflict markers in four files as
its only commit, which is why this exists.

Assisted-by: LLM
Signed-off-by: Yan Bondarenko <[email protected]>

Backport of #4254 to release-1.6.

Cluster-wide migration settings could only be applied by patching the KubeVirt
CR: the kubevirt chart did not render `migrations`, and the platform bundle did
not forward it. The optional `kubevirt.migrations` platform value now passes
through the generated Package to `spec.configuration.migrations`, and a hand
patch of that Package is undone on the next platform render, so this hop is the
only supported setter.

Four differences from main, all from release-1.6 predating the
disabledFeatureGates work:

- platform values gains a `kubevirt` block holding `migrations` alone, and the
  iaas bundle gains only the migrations hop;
- the wiring test takes the four migrations cases and the case for a null
  `kubevirt` block, without the assertions that belong to disabledFeatureGates
  cases absent here;
- update_idempotency_test.sh gains `run_update_logged`, which arrived on main
  alongside that work and the new cases need;
- the kubevirt Makefile header counts six sed patches rather than five.

Verified on this branch: 9 kubevirt chart tests, 31 platform wiring tests (102
across the platform suite), and update_idempotency_test PASS under GNU make and
sed. Removing the new awk guard from the Makefile turns that test red naming the
migrations block, so the ported guard is not decorative. On this line
(.Values.kubevirt).migrations is the only reader of .Values.kubevirt, and
rewriting it as .Values.kubevirt.migrations turns the null-block case red with a
nil pointer.

The automated backport in #4322 stopped with conflict markers in four files as
its only commit, which is why this exists.

Assisted-by: LLM
Signed-off-by: Yan Bondarenko <[email protected]>

Backport of #4254 to release-1.6.

Cluster-wide migration settings could only be applied by patching the KubeVirt
CR: the kubevirt chart did not render `migrations`, and the platform bundle did
not forward it. The optional `kubevirt.migrations` platform value now passes
through the generated Package to `spec.configuration.migrations`, and a hand
patch of that Package is undone on the next platform render, so this hop is the
only supported setter.

Four differences from main, all from release-1.6 predating the
disabledFeatureGates work:

- platform values gains a `kubevirt` block holding `migrations` alone, and the
  iaas bundle gains only the migrations hop;
- the wiring test takes the four migrations cases and the case for a null
  `kubevirt` block, without the assertions that belong to disabledFeatureGates
  cases absent here;
- update_idempotency_test.sh gains `run_update_logged`, which arrived on main
  alongside that work and the new cases need;
- the kubevirt Makefile header counts six sed patches rather than five.

Verified on this branch: 9 kubevirt chart tests, 31 platform wiring tests (102
across the platform suite), and update_idempotency_test PASS under GNU make and
sed. Removing the new awk guard from the Makefile turns that test red naming the
migrations block, so the ported guard is not decorative. On this line
(.Values.kubevirt).migrations is the only reader of .Values.kubevirt, and
rewriting it as .Values.kubevirt.migrations turns the null-block case red with a
nil pointer.

The automated backport in #4322 stopped with conflict markers in four files as
its only commit, which is why this exists.

Assisted-by: LLM
Signed-off-by: Yan Bondarenko <[email protected]>

… through platform values (#4402)

This reopens a fork backport from a branch in this repository so its CI
can run. The commit is the one from #4339 by @yankawai, unchanged. On
release-1.6 the pull-request CI pushes the images it builds, and a run
from a fork has no registry credentials, so #4339 stopped at the build
jobs and never reached e2e. The description below is the author's.

## What this PR does

Manual backport of #4254 to `release-1.6`.

The automated backport, #4322, stopped with conflict markers in four
files as its only commit, so it is red on DCO and unmergeable as it
stands.

Every conflict has the same cause: the `kubevirt.disabledFeatureGates`
work landed on main after 1.6 was cut, and the cherry-pick carried it
into hunks this line does not have. Four differences follow:

- platform values gains a `kubevirt` block holding `migrations` alone,
and the iaas bundle gains only the migrations hop;
- the wiring test takes the four migrations cases and the case for a
null `kubevirt` block, without the assertions that belong to
disabledFeatureGates cases this line does not have;
- `update_idempotency_test.sh` gains `run_update_logged`, a four-line
helper that arrived on main with that work and the new cases need;
- the kubevirt Makefile header counts six sed patches rather than five.

Verified on this branch: 9 kubevirt chart tests, 31 platform wiring
tests (102 across the platform suite), and `update_idempotency_test`
PASS under GNU make and sed. Removing the new awk guard from the
Makefile turns that test red naming the migrations block, so the ported
guard is doing work. On this line `(.Values.kubevirt).migrations` is the
only reader of `.Values.kubevirt`; rewriting it as
`.Values.kubevirt.migrations` turns the null-block case red with a nil
pointer.

Feature summary, unchanged from #4254: cluster-wide migration settings
could only be applied by patching the KubeVirt CR, because the kubevirt
chart did not render `migrations` and the platform bundle did not
forward it. `kubevirt.migrations` now passes through the generated
Package to `spec.configuration.migrations`. A hand patch of that Package
is undone on the next platform render, so this hop is the only supported
setter.

```yaml
kubevirt:
  migrations:
    bandwidthPerMigration: 625M
    parallelMigrationsPerCluster: 2
    parallelOutboundMigrationsPerNode: 1
```

### Screenshots

Not a UI change.

### Downstream repositories

Walked the trigger map against the diff: platform values, the iaas
bundle and the kubevirt chart. The v1.6 reference page of the platform
values had no `kubevirt` section, so the row goes there as a follow-up
that should land with this backport.

- [ ] No downstream repository is affected by this change
- [x] [cozystack/website](https://github.com/cozystack/website) -
follow-up: cozystack/website#705

### Release note

```release-note
feat(kubevirt): expose `kubevirt.migrations` in the platform values and forward it to `spec.configuration.migrations` on the KubeVirt CR, so live-migration bandwidth and parallelism can be set without patching a Package that the platform re-renders.
```