RFR: 8355372: GenShen: Test gc/shenandoah/generational/TestOldGrowthTriggers.java fails with UseCompactObjectHeaders enabled [v2]

[William Kemper]

> Add a test case for `-XX:+UseCompactObjectHeaders`, increase pressure on old generation. I ran the test (which includes a compact object headers case now) fifty times without failure.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Clarify cases with comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24888/files
  - new: https://git.openjdk.org/jdk/pull/24888/files/9c991cfa..70b36ac5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24888&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24888&range=00-01

  Stats: 5 lines in 1 file changed: 3 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24888.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24888/head:pull/24888

PR: https://git.openjdk.org/jdk/pull/24888