Remove configs for bots that were removed. Dedicated focal bots and
x86 gcc bots.

Bug: chromium:1307180, v8:13005
Change-Id: I482829f6644642b3d9fe1b380b2a3edaba2045d4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3747869Reviewed-by: Alexander Schulze <alexschulze@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81561}