kv/kvserver: TestStoreRangeMergeSplitRace_MergeWins failed

kv/kvserver.TestStoreRangeMergeSplitRace_MergeWins [failed](https://mesolite.cluster.engflow.com/invocations/default/b6202731-e6ec-40a9-acef-9c28f03dd7f0?testReportRun=2&testReportShard=4&testReportAttempt=1#targets-Ly9wa2cva3Yva3ZzZXJ2ZXI6a3ZzZXJ2ZXJfdGVzdA==) on master @ [fd76d6db170472d99ccb63d72a6b7a630a0c45d0](https://github.com/cockroachdb/cockroach/commits/fd76d6db170472d99ccb63d72a6b7a630a0c45d0):

```
=== RUN TestStoreRangeMergeSplitRace_MergeWins
test_log_scope.go:172: test logs captured to: outputs.zip/logTestStoreRangeMergeSplitRace_MergeWins4114259662
test_log_scope.go:82: use -show-logs to present logs inline
test_server_shim.go:146: using test tenant configuration from testserver factory defaults
client_merge_test.go:1684: merge failed: checking RHS manifest before merge: descriptor generation mismatch: expected 2, found 3
panic.go:694: -- test log scope end --
test logs left over in: outputs.zip/logTestStoreRangeMergeSplitRace_MergeWins4114259662
--- FAIL: TestStoreRangeMergeSplitRace_MergeWins (5.43s)
```

Parameters:
- attempt=1
- race=true
- run=2
- shard=4
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

/cc @cockroachlabs/kv-triage

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Jira issue: CRDB-67974