* PR checks: Only run Swift build command on MacOS
* PR checks: update to only test Swift on MacOS
* Log warning if workflow is running Swift on Ubuntu
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Co-authored-by: Andrew Eisenberg <aeisenberg@github.com>
Build tracing using CLIs before 2.7.3 no longer works with the most
recent update to the `ubuntu-22.04` runner image.
With this new logic, we can remove the workarounds around testing
`windows-2019` and `windows-2022`.