release-25.4: workflows: update names of GitHub Action runner groups

[rickystewart]

Backport 1/1 commits from #154698 on behalf of @rickystewart.

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These are the new-style names that will make it easier to migrate to Ubuntu 22.04+ when the time comes.

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Release justification: Non-production code changes

[blathers-crl]

Thanks for opening a backport.

Before merging, please confirm that the change does not break backwards compatibility and otherwise complies with the backport policy. Include a brief release justification in the PR description explaining why the backport is appropriate. All backports must be reviewed by the TL for the owning area. While the stricter LTS policy does not yet apply, please exercise judgment and consider gating non-critical changes behind a disabled-by-default feature flag when appropriate.

[cockroach-teamcity]

This change is