sql: TestExperimentalRelocateVoters failed

sql.TestExperimentalRelocateVoters [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsIbmCloudLinuxS390x_UnitTestsS390x/21513367?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsIbmCloudLinuxS390x_UnitTestsS390x/21513367?buildTab=artifacts#/) on master @ [11498498a6837bce989898f7f06648a57215e9ce](https://github.com/cockroachdb/cockroach/commits/11498498a6837bce989898f7f06648a57215e9ce):

```
=== RUN TestExperimentalRelocateVoters
test_log_scope.go:172: test logs captured to: /artifacts/tmp/_tmp/bd99d454bce9552cf84977d80c7c9635/logTestExperimentalRelocateVoters1767474732
test_log_scope.go:82: use -show-logs to present logs inline
multitenant_admin_function_test.go:845: -- test log scope end --
test logs left over in: /artifacts/tmp/_tmp/bd99d454bce9552cf84977d80c7c9635/logTestExperimentalRelocateVoters1767474732
--- FAIL: TestExperimentalRelocateVoters (62.46s)
=== RUN TestExperimentalRelocateVoters/ALTER_TABLE_x_EXPERIMENTAL_RELOCATE_VOTERS
multitenant_admin_function_test.go:186: condition failed to evaluate within 45s: from multitenant_admin_function_test.go:194: waiting for 1 ranges with LEARNER replicas to clear

goroutine dump: /artifacts/tmp/_tmp/bd99d454bce9552cf84977d80c7c9635/goroutine_dump_2939348994.txt
--- FAIL: TestExperimentalRelocateVoters/ALTER_TABLE_x_EXPERIMENTAL_RELOCATE_VOTERS (61.70s)
```
Help

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

/cc @cockroachlabs/sql-foundations

[Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-68331

Start with TestExperimentalRelocateVoters in multitenant_admin_function_test.go and reproduce the failure using the linked TeamCity artifacts. Inspect the captured test logs and goroutine dump to determine why learner replicas do not clear within 45 seconds. Done means the test completes successfully on the reported s390x configuration.

Written by the indexing model from the issue text.