Remove the common base class of MarkCompactCollector and
MinorCompactCollector as a cleanup.

Change-Id: Ib6a931b2bd397ac7c9425b0e268b847a38125a57
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3610424Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80243}