RFR: 8316632: Shenandoah: Raise OOME when gc threshold is exceeded [v6]

[William Kemper]

> Shenandoah will run back-to-back full GCs and _almost_ grind mutator progress to a halt before eventually exhausting memory. This change will have Shenandoah raise a gc threshold exceeded exception if the collector fails to make progress after `ShenandoahNoProgressThreshold` full GC cycles (default is 3).

William Kemper has updated the pull request incrementally with two additional commits since the last revision:

 - Remove unnecessary nesting and other differences
 - Update formatting

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15852/files
  - new: https://git.openjdk.org/jdk/pull/15852/files/868af376..4154370c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15852&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15852&range=04-05

  Stats: 56 lines in 2 files changed: 17 ins; 16 del; 23 mod
  Patch: https://git.openjdk.org/jdk/pull/15852.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15852/head:pull/15852

PR: https://git.openjdk.org/jdk/pull/15852