[BUG] org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testReplicaAlreadyAtCheckpoint is flaky

[kasundra07]

Describe the bug
The test case org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testReplicaAlreadyAtCheckpoint is flaky:

java.lang.AssertionError:  inconsistent generation 
	at __randomizedtesting.SeedInfo.seed([138297ACFE85FB99]:0)
	at org.opensearch.index.translog.transfer.TranslogCheckpointTransferSnapshot$Builder.build(TranslogCheckpointTransferSnapshot.java:180)
	at org.opensearch.index.translog.RemoteFsTranslog.upload(RemoteFsTranslog.java:338)
	at org.opensearch.index.translog.RemoteFsTranslog.prepareAndUpload(RemoteFsTranslog.java:310)
	at org.opensearch.index.translog.RemoteFsTranslog.sync(RemoteFsTranslog.java:365)
	at org.opensearch.index.translog.InternalTranslogManager.syncTranslog(InternalTranslogManager.java:196)
	at org.opensearch.index.engine.InternalEngine.syncTranslog(InternalEngine.java:610)
	at org.opensearch.index.shard.IndexShard.postActivatePrimaryMode(IndexShard.java:3449)
	at org.opensearch.index.shard.IndexShard.lambda$updateShardState$4(IndexShard.java:727)
	at org.opensearch.index.shard.IndexShard$5.onResponse(IndexShard.java:4052)
	at org.opensearch.index.shard.IndexShard$5.onResponse(IndexShard.java:4022)
	at org.opensearch.index.shard.IndexShard.lambda$asyncBlockOperations$37(IndexShard.java:3973)
	at org.opensearch.core.action.ActionListener$1.onResponse(ActionListener.java:82)
	at org.opensearch.index.shard.IndexShardOperationPermits$1.doRun(IndexShardOperationPermits.java:157)
	at org.opensearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:908)
	at org.opensearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:52)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1583)

To Reproduce

./gradlew ':server:internalClusterTest' --tests "org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testReplicaAlreadyAtCheckpoint" -Dtests.seed=138297ACFE85FB99

Expected behavior
The test must always pass

Additional context
https://build.ci.opensearch.org/job/gradle-check/30101/testReport/junit/org.opensearch.remotestore/SegmentReplicationUsingRemoteStoreIT/testReplicaAlreadyAtCheckpoint/

[mch2]

This cause looks identical to #10902. @kasundra07 was this build on 2.x or main?

The fix for this is in main but had not yet landed in 2.x - #11168

edit - just merged the fix to 2.x.

[kartg]

It appears that the fix referenced above has resolved the flakiness here. I was unable to repro the inconsistent generation issue even after repeatedly running the repro command from this run several thousand times:

./gradlew ':server:internalClusterTest' --tests "org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testReplicaAlreadyAtCheckpoint" -Dtests.seed=138297ACFE85FB99 -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=lt -Dtests.timezone=Europe/Warsaw -Druntime.java=21

Also, no open items reference this flaky failure. Note that when using -Dtests.iters parameter to repeatedly run the test, I did run into other failures, though these are unrelated to the flakiness in this issue. Examples:

• Test suite timeout - mitigated by overriding the suite timeout using -Dtests.timeoutSuite
• java.lang.AssertionError: a started primary with non-pending operation term must be in primary mode - recurrence of [BUG] org.opensearch.cluster.MinimumClusterManagerNodesIT.testThreeNodesNoClusterManagerBlock flaky #10006

I'm opting to close this issue as a fixed flaky test. Please reopen if this signature resurfaces.