[build] Remove obsolete builders from MB config

TBR=sergiyb@chromium.org
NOTRY=true

Bug: v8:8009
Change-Id: I044fffd027f76ad8d76b6546af508e7df7486a61
Reviewed-on: https://chromium-review.googlesource.com/1160522Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54870}

infra/mb/mb_config.pyl

@@ -97,9 +97,6 @@
       # Sanitizers.
       'V8 Linux64 ASAN': 'release_x64_asan',
       'V8 Linux64 TSAN - builder': 'release_x64_tsan',
-      # TODO(machenbach): Remove when turning into testers on infra side.
-      'V8 Linux64 TSAN': 'release_x64_tsan',
-      'V8 Linux64 TSAN - concurrent marking': 'release_x64_tsan',
       'V8 Linux - arm64 - sim - MSAN': 'release_simulate_arm64_msan',
       # Misc.
       'V8 Linux gcc 4.8': 'release_x86_gcc',