basalt-26.3.2-rc-20260908: sql/stmtdiagnostics: TestTxnRegistry_CancelRequest_MultiNode failed

sql/stmtdiagnostics.TestTxnRegistry_CancelRequest_MultiNode [failed](https://mesolite.cluster.engflow.com/invocations/default/4e6b3e4b-4f3a-4ae0-ac38-acabe7fa7d66?testReportRun=1&testReportShard=3&testReportAttempt=1#targets-Ly9wa2cvc3FsL3N0bXRkaWFnbm9zdGljczpzdG10ZGlhZ25vc3RpY3NfdGVzdA==) on basalt-26.3.2-rc-20260908 @ [807558e5e81666af257c811e925e4cae570abc28](https://github.com/cockroachdb/cockroach/commits/807558e5e81666af257c811e925e4cae570abc28):

```
=== RUN TestTxnRegistry_CancelRequest_MultiNode
test_log_scope.go:172: test logs captured to: outputs.zip/logTestTxnRegistry_CancelRequest_MultiNode2971224580
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.
=== RUN TestTxnRegistry_CancelRequest_MultiNode/valid_conditional_request
```

Parameters:
- attempt=1
- race=true
- run=1
- shard=3
Help

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

Same failure on other branches

- #174820 basalt-26.3: sql/stmtdiagnostics: TestTxnRegistry_CancelRequest_MultiNode failed [C-test-failure O-robot T-sql-queries branch-basalt-26.3]
- #173407 sql/stmtdiagnostics: TestTxnRegistry_CancelRequest_MultiNode failed [C-test-failure O-robot T-sql-queries branch-master]

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

Start with sql/stmtdiagnostics.TestTxnRegistry_CancelRequest_MultiNode and reproduce it with the reported race=true parameters. Inspect the captured outputs.zip/logTestTxnRegistry_CancelRequest_MultiNode2971224580 logs and the test_server_shim.go guidance; done means identifying the failure cause and restoring a passing test.

Written by the indexing model from the issue text.