RFR: 8317228: GC: Make TestXXXHeapSizeFlags use createTestJvm [v5]

[Leo Korinth]

> Minor testing done, I will test more later with other fixes.

Leo Korinth has updated the pull request incrementally with one additional commit since the last revision:

  add explanation: test is sensitive to certain flags and might fail when flags are passed using -vmoptions and -javaoptions

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15986/files
  - new: https://git.openjdk.org/jdk/pull/15986/files/a5b87914..8491a679

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15986&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15986&range=03-04

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15986.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15986/head:pull/15986

PR: https://git.openjdk.org/jdk/pull/15986