RFR: 8329521: Serial: Rename MarkSweep to SerialFullGC

[Guoxiong Li]

Hi all,

This patch renames the `MarkSweep` to `SerialFullGC` and fixes some comments related to `MarkSweep`.

The tests `make test-tier1_gc` passed locally. Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - JDK-8329521

Changes: https://git.openjdk.org/jdk/pull/18619/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18619&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329521
  Stats: 1631 lines in 12 files changed: 806 ins; 807 del; 18 mod
  Patch: https://git.openjdk.org/jdk/pull/18619.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18619/head:pull/18619

PR: https://git.openjdk.org/jdk/pull/18619