Summary

3.x version of #5440

• migrate more uses of fs.promises; use node: protocol. I had missed a lot because my vs code search index was off.
• fix size comparison for slim files when the branch is dirty. I fixed this by preferring +slim. to + in the regex. It was only matching on the latter even for the slim file.
• make compare size cache readable for manual edits. This is in lieu of more complicated options added to the build command. It's not hard to just edit the JSON, but it might as well be readable.
• Fix worker restarts for when a browser fails the acknowledgement test (I just broke this in Tests: add --hard-retries option to test runner #5439 )

Checklist

• New tests have been added to show the fix or feature works
• If needed, a docs issue/PR was created at https://github.com/jquery/api.jquery.com