RFR: 8311775: [TEST] duplicate verifyHeapDump in several tests [v3]

[Yi Yang]

> This is a follow-up patch of #13667. verifyHeapDump is duplicated in several tests, this patch tries to consolidate them into one method.

Yi Yang has updated the pull request incrementally with one additional commit since the last revision:

  review from Alex

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15202/files
  - new: https://git.openjdk.org/jdk/pull/15202/files/ac581090..b6a528a2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15202&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15202&range=01-02

  Stats: 13 lines in 4 files changed: 0 ins; 9 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/15202.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15202/head:pull/15202

PR: https://git.openjdk.org/jdk/pull/15202