roachtest: cluster_creation failed

roachtest.cluster_creation [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyIbmBazel/19761332?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyIbmBazel/19761332?buildTab=artifacts#/ycsb/D/nodes=3/cpu=32/isolation-level=read-committed) on master @ [cb9aa6e26818595037d719c028117f4927c6ab58](https://github.com/cockroachdb/cockroach/commits/cb9aa6e26818595037d719c028117f4927c6ab58):

```
test ycsb/D/nodes=3/cpu=32/isolation-level=read-committed failed: (test_runner.go:850).func4: invalid number of cpus 32 for IBM [owner=test-eng]
```

Parameters:
- cloud=ibm
- coverageBuild=false
- cpu=32
- runtimeAssertionsBuild=false
- ssd=0
Help

See: [roachtest README](https://github.com/cockroachdb/cockroach/blob/master/pkg/cmd/roachtest/README.md)

See: [How To Investigate \(internal\)](https://cockroachlabs.atlassian.net/l/c/SSSBr8c7)

/cc @cockroachdb/test-eng

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

Jira issue: CRDB-50925

Start with the linked TeamCity log and artifacts, then read pkg/cmd/roachtest/README.md and the failure location at test_runner.go:850. Trace why the IBM run rejects cpu=32 and determine the expected behavior for cluster_creation; done means the reported IBM roachtest configuration no longer fails for this invalid-CPU error.

Written by the indexing model from the issue text.