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

This reverts commit 4cfd0a0dd30f07a2d9ca4b9943b0164f4c14c4a0.

TBR=maruel

BUG=236893

Review URL: https://codereview.chromium.org/45043002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231056 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231056