Tests: share queue/browser handling for all worker types

[timmywil]

Summary

3.x version of #5460

• one queue to rule them all: browserstack, selenium, and jsdom
• retries and hard retries are now supported in selenium
• selenium tests now re-use browsers in the same way as browserstack

Sample test run to make sure nothing broke: https://github.com/timmywil/jquery/actions/runs/8509342926

Checklist

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

[timmywil]

yes, the commit was cherry-picked.