roachtest: cluster_creation failed

roachtest.cluster_creation [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyIbmBazel/21260484?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyIbmBazel/21260484?buildTab=artifacts#/kv0/enc=false/nodes=3/cpu=32/seq) on release-26.1 @ [95a4771368c0790a26239cb6be532865c8227967](https://github.com/cockroachdb/cockroach/commits/95a4771368c0790a26239cb6be532865c8227967):

```
test kv0/enc=false/nodes=3/cpu=32/seq failed: (test_runner.go:991).func4: invalid number of cpus 32 for IBM [owner=test-eng]
```

Parameters:
- cloud=ibm
- coverageBuild=false
- cpu=32
- diskCount=0
- runtimeAssertionsBuild=false
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-61635

Start with the failure at test_runner.go:991 and read the roachtest README for cluster_creation investigation guidance. Use the linked TeamCity log and artifacts to confirm why cpu=32 is invalid for IBM, then compare the relevant roachtest configuration or validation path. Done means the IBM cluster_creation case no longer rejects a valid configuration and the regression is covered by an appropriate test.

Written by the indexing model from the issue text.