In another commit of the same PR 27774, I don't even see test_regrtest in the list of the "10 slowest tests", so test_regrtest took less than "test_socket: 46.4 sec".

If test_regrtest is killed after 20 minutes, it's likely that it was stuck somewhere.

test_tools_script_run_tests() runs Tools/scripts/run_tests.py with command line arguments.

In the past, I see many issues with PermissionError: something prevents to delete a directory on Windows. I never understood what.

regrtest creates a temporary directory, run a process in this directory, and then removes the directory. Here, something is stuck.