RFR: 8304015: G1: Metaspace-induced GCs should not trigger maximal compaction

[Ivan Walulya]

Hi all,

Please review this small cleanup to remove triggering maximal compaction on Metaspace-induced full-GCs.

Testing: Tier1.

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Commit messages:
 - not an explicit GC
 - clear_all_soft_refs shouldn't always trigger full compaction

Changes: https://git.openjdk.org/jdk/pull/12987/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12987&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304015
  Stats: 6 lines in 1 file changed: 0 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12987.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12987/head:pull/12987

PR: https://git.openjdk.org/jdk/pull/12987