PHOENIX-7562 Add HAGroupStore Metrics2 observability

[ritegarg]

Expose focused per-HA-group observability without coupling metrics to HA decisions.

What changes were proposed in this pull request?

• Add a process-lifetime Hadoop Metrics2 source per HA group with 5 gauges, 6 counters, and 1 listener-latency histogram.
• Export zero-is-good local-cache and peer-visibility status gauges, stable non-ordinal HA state codes, and selected episode/failure counters.
• Tag each source by HA group and safely quote its JMX identity.
• Add focused unit and two-cluster integration coverage for the exported contract and runtime behavior.

Why are the changes needed?

HAGroupStore currently relies on logs for cache health, peer reachability, state divergence, fail-closed behavior, background failures, and slow synchronous listeners. These metrics provide alertable current state and targeted diagnostics while remaining independent of HA control flow.

Does this PR introduce any user-facing change?

Yes. RegionServers expose new HAGroupStore Metrics2/JMX metrics. There is no SQL, JDBC, or HA decision behavior change.

How was this patch tested?

• Unit tests:
  mvn -pl phoenix-core -am -DskipITs -Dtest=HAGroupStoreRecordTest,HAGroupStoreMetricsSourceImplTest -Dsurefire.failIfNoSpecifiedTests=false -DfailIfNoTests=false test
• Integration tests:
  mvn -pl phoenix-core -am -Dtest=NoSuchUnitTest -Dsurefire.failIfNoSpecifiedTests=false -DfailIfNoTests=false -Dit.test=HAGroupStoreMetricsIT -DskipParallelStatsEnabledTests=true -DskipParallelStatsDisabledTests=true verify
• Result: 27 unit tests and 7 integration tests passed.

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