Use GHA runners instead of custom runners

[jakebailey]

Testing to see if it's even worth it to use custom runners.

Before:

These are the jobs on custom runners:

• race: 11m25s
• release-build: 10m59s

After:

So:

• race: 20m35s
• release-build: 17m17s

So, something like twice as slow.

But, windows-latest already takes nearly 19 minutes. So, why bother having these runners?

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR switches select CI jobs from custom self-hosted runners (1ES pool) to GitHub-hosted runners to evaluate performance and whether custom runners are worth maintaining.

Changes:

• Move release-build job execution to ubuntu-latest GitHub-hosted runner.
• Update the matrix entry for the “race mode” job to run on ubuntu-latest instead of the self-hosted runner pool.

[RyanCavanaugh]

Either way