RFR: 8297742: Combine vmTestbase/nsk/monitoring/ThreadMXBean/resetPeakThreadCount tests [v3]

[Alex Menkov]

> The fix combines almost the same tests to 1 test to remove code duplication

Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:

  Fixed comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11400/files
  - new: https://git.openjdk.org/jdk/pull/11400/files/393f1252..f3a2411c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11400&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11400&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/11400.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11400/head:pull/11400

PR: https://git.openjdk.org/jdk/pull/11400