Also remove tests in //tools_webrtc/mb/mb_unittest.py that are testing exclusively code in //tools/mb/mb.py.
Bug: webrtc:13662
Change-Id: Ifdfbe26c11f7c315e307856b1d3ab06483d57641
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/260041
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#36651}