Flaky test TestInterceptor/reftable_migration=true

Steps

• This issue has been assigned the current milestone

• Flaky test has been quarantined with testhelper.SkipQuarantinedTest.

• Flaky test has been fixed and quarantine removed.

• https://gitlab.com/gitlab-org/gitaly/-/jobs/10770291607

• https://gitlab.com/gitlab-org/gitaly/-/jobs/10780735048#L1030

• https://gitlab.com/gitlab-org/gitaly/-/jobs/10792066407

time="2025-07-22T12:34:21Z" level=error msg="partition failed" error="apply log entry: update: apply operations: remove: remove /tmp/gitaly-2607579308/2200024106/storages.d/default/@cluster/repositories/4e/07/3/refs/heads: directory not empty" partition_id=4 partition_state_directory=+gitaly/partitions/4b/22/4 storage=default