[improve][monitor] Upgrade Dropwizard Metrics to 4.2.39 and HdrHistogram to 2.2.2 - #26353

Motivation

Dropwizard Metrics is two minor lines behind (4.1.12.1, released in 2020) and HdrHistogram is behind
as well. Neither has any relationship to the Prometheus simpleclient, so they can be updated
independently of any Prometheus client_java migration.

Modifications

gradle/libs.versions.toml:

Plus the corresponding jar names in the server distribution LICENSE.bin.txt.

Dropwizard Metrics 4.2.0 was an additive release — support for Jersey 3.x, Jetty 10/11, the
jakarta.servlet namespace and Caffeine 3.x — with no documented API removals. Pulsar uses
metrics-core, metrics-graphite and metrics-jvm.

Note on the Prometheus client

prometheus (simpleclient) 0.16.0 and prometheus-jmx 0.16.1 are deliberately not touched here.
simpleclient 0.16.0 is the final release of that line, and moving off it is a code migration rather
than a version bump:

• 64 Java files across 12 modules import io.prometheus.client;
• org.apache.bookkeeper.stats:prometheus-metrics-provider:4.18.0 has hard compile dependencies on
  simpleclient, simpleclient_hotspot and simpleclient_servlet, and ships in the server
  distribution;
• PrometheusMetricsGeneratorUtils scrapes CollectorRegistry.defaultRegistry, the shared registry
  that BookKeeper and ZooKeeper publish into.

prometheus-jmx 1.6.0 is specifically coupled to that migration: it depends on
prometheus-metrics-core 1.7.0 rather than simpleclient, and in 1.x io.prometheus.jmx.JmxCollector
becomes a collector on the new registry. RuntimeUtils.registerDefaultCollectors() registers it into
FunctionCollectorRegistry, which extends the simpleclient CollectorRegistry, so that bump
requires migrating the pulsar-functions instance metrics stack first.

Verifying this change

• Make sure that the change passes the CI checks.

This change is a trivial rework / code cleanup without any test coverage.

Verified locally with ./gradlew sanityCheck and ./gradlew checkBinaryLicense.

Does this pull request potentially affect one of the following parts:

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment