seaweedfs-filer connections to PostgreSQL is unlimited #2534

Hi! On load testing found errors in seaweedfs-filer too many connections.
On the PostgreSQL side connections limit=100.

On Filer side some pameters can be set: https://github.com/seaweedfs/seaweedfs/blob/4.05/weed/filer/postgres2/postgres2_store.go#L55-L57

via .Values.filer.extraEnvironmentVars
or .Values.filer.extraArgs
or filer.toml

For example (via extraEnvironmentVars):
ENV: WEED_POSTGRES2_CONNECTION_MAX_OPEN=50, WEED_POSTGRES2_CONNECTION_MAX_IDLE=10, WEED_POSTGRES2_CONNECTION_MAX_LIFETIME_SECONDS=300

N.B.! This limits depends on filer replicas count.

Resume:
for high-load Seaweed instances configuration connection limits both sides - should have. Defaults - must have.