release-24.3.21-rc: workflows: update names of GitHub Action runner groups

[rickystewart]

Backport 1/1 commits from #154794 on behalf of @rickystewart.

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Backport 1/1 commits from #154698.

/cc @cockroachdb/release

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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.

Release justification: Non-production code changes

[blathers-crl]

Thanks for opening a backport.

Before merging, please confirm that it falls into one of the following categories (select one):

• Non-production code changes. Includes test-only changes, build system changes, etc.
• Fixes for serious issues. Defined in the policy as correctness, stability, or security issues, data corruption/loss, significant performance regressions, breaking working and widely used functionality, or an inability to detect and debug production issues.
• Other approved changes. These changes must be gated behind a disabled-by-default feature flag unless there is a strong justification not to.

Add a brief release justification to the PR description explaining your selection.

Also, confirm that the change does not break backward compatibility and complies with all aspects of the backport policy.

All backports must be reviewed by the TL and EM for the owning area.

[blathers-crl]

✅ PR #155098 is compliant with backport policy

Confidence: high
Backward compatible: true
Explanation: The pull request is compliant with the CockroachDB backport policy for non-production changes. It modifies a file within the GitHub Actions workflow, which falls under the category of changes affecting CI and build processes, specifically exempt under the non-production file patterns. The PR also contains a 'Release justification: Non-production code changes' line in the body, exempting it from standard backport policy requirements according to the exception for release justification. As this change only affects the workflow files used by GitHub Actions, it does not introduce any production-related modifications, feature flags, or backward compatibility concerns.

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is