HBASE-30165 Preserve sibling replicas in location cache

[1fanwang]

The async client can update region replica locations one at a time after a move. Before this change, caching replicas 0, 1, and 2 separately left only one replica in the cache, so later lookups for the sibling replicas missed.

Single-location updates now use a synchronized path that replaces only the matching replica. Different primary regions still use the existing replacement path, and complete metadata responses still control the replica-list length.

Jira: https://issues.apache.org/jira/browse/HBASE-30165

Verification

The regression exercises AsyncNonMetaRegionLocator.addLocationToCache in ascending and descending replica order. It also checks that a different primary region with the same start key replaces stale siblings.

Commands and raw output

Before, on d11cafefbcbe8b356aaede41fcf9b153dbf2c2bc with only the regression test applied:

$ JAVA_HOME=$(/usr/libexec/java_home -v 17) mvn -pl hbase-client -Dtest=TestAsyncRegionLocationCache test
[ERROR] Tests run: 2, Failures: 1, Errors: 0, Skipped: 0
[ERROR] TestAsyncRegionLocationCache.testAddingIndividualReplicasPreservesSiblings:55 [0, 1, 2] ==> expected: <3> but was: <1>
[INFO] BUILD FAILURE

After:

$ JAVA_HOME=$(/usr/libexec/java_home -v 17) mvn -pl hbase-client -Dtest=TestAsyncRegionLocationCache test
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0
[INFO] BUILD SUCCESS

The only full-module failure is also present on unmodified master:

$ JAVA_HOME=$(/usr/libexec/java_home -v 17) mvn -pl hbase-client test
[ERROR] TestRegistryEndpointsRefresher.testDurationBetweenRefreshes:121 40 ==> expected: <true> but was: <false>
[ERROR] Tests run: 309, Failures: 1, Errors: 0, Skipped: 0

$ git checkout d11cafefbcbe8b356aaede41fcf9b153dbf2c2bc
$ JAVA_HOME=$(/usr/libexec/java_home -v 17) mvn -pl hbase-client -Dtest=TestRegistryEndpointsRefresher#testDurationBetweenRefreshes test
[ERROR] TestRegistryEndpointsRefresher.testDurationBetweenRefreshes:121 36 ==> expected: <true> but was: <false>
[INFO] BUILD FAILURE