Revert 231359 "GTTF: make sharding_supervisor.py use --brave-new..."

This broke Mac interactive_ui_tests

> GTTF: make sharding_supervisor.py use --brave-new-test-launcher
> 
> - browser tests use parallel jobs by default (except interactive_ui_tests)
> - sharding + PRE_ tests are handled correctly
> - .isolate files updated
> 
> BUG=236893
> R=maruel@chromium.org, sky@chromium.org
> 
> Review URL: https://codereview.chromium.org/46023003

TBR=phajdan.jr@chromium.org

Review URL: https://codereview.chromium.org/48113008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231371 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231371