release-26.3: sql/tests: TestSplitAtTableBoundary failed

sql/tests.TestSplitAtTableBoundary [failed](https://mesolite.cluster.engflow.com/invocations/default/c72e94ce-de35-42fe-874a-eedbb00f518a?testReportRun=1&testReportShard=16&testReportAttempt=1#targets-Ly9wa2cvc3FsL3Rlc3RzOnRlc3RzX3Rlc3Q=) on release-26.3 @ [e2da48c156e83f67f91e9c445c8c9b5d90098afc](https://github.com/cockroachdb/cockroach/commits/e2da48c156e83f67f91e9c445c8c9b5d90098afc):

```
=== RUN TestSplitAtTableBoundary
test_log_scope.go:172: test logs captured to: outputs.zip/logTestSplitAtTableBoundary2048854380
test_log_scope.go:82: use -show-logs to present logs inline
test_server_shim.go:168: automatically injected a shared process virtual cluster under test; see comment at top of test_server_shim.go for details.
table_split_test.go:53: condition failed to evaluate within 3m45s: from table_split_test.go:60: expected range start key /Tenant/10/Table/106; got /Tenant/10/Table/84

goroutine dump: /mnt/engflow/worker/work/0/exec/bazel-out/k8-fastbuild/testlogs/pkg/sql/tests/tests_test/shard_16_of_16_run_1_of_3/test.outputs/goroutine_dump_1426718042.txt
panic.go:694: -- test log scope end --
test logs left over in: outputs.zip/logTestSplitAtTableBoundary2048854380
--- FAIL: TestSplitAtTableBoundary (1609.46s)
```

Parameters:
- attempt=1
- race=true
- run=1
- shard=16
Help

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

Same failure on other branches

- #174815 release-26.2: sql/tests: TestSplitAtTableBoundary failed [C-test-failure O-robot T-sql-queries branch-release-26.2 release-blocker]
- #174750 sql/tests: TestSplitAtTableBoundary failed [C-test-failure O-robot T-sql-queries branch-master release-blocker]
- #174697 basalt-26.3: sql/tests: TestSplitAtTableBoundary failed [C-test-failure O-robot T-sql-queries branch-basalt-26.3 release-blocker]

[This test on roachdash](https://roachdash.crdb.dev/?filter=status:open%20t:.*TestSplitAtTableBoundary.*&sort=title+created&display=lastcommented+project) | [Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-68013

Start with pkg/sql/tests/table_split_test.go, especially TestSplitAtTableBoundary and the failure at line 60. Review the captured test logs and goroutine dump from outputs.zip, then reproduce the failure with the shown race, shard, and release-26.3 parameters. Done means identifying and correcting the cause so the test reliably observes the expected range start key.

Written by the indexing model from the issue text.