RFR: 8341060: Cleanup statics in HeapDumper

[Alex Menkov]

The fix cleans up static variables/methods in HeapDumper.
See jira for details.

Testing:
  heap dump-related tests (test/hotspot/jtreg/serviceability, test/hotspot/jtreg/compiler/c2/TestReduceAllocationAndHeapDump.java, test/hotspot/jtreg/runtime/ErrorHandling, test/hotspot/jtreg/gc/epsilon, test/jdk/sun/tools/jhsdb, test/jdk/sun/tools/jmap, test/jdk/com/sun/management/HotSpotDiagnosticMXBean)

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Commit messages:
 - fix

Changes: https://git.openjdk.org/jdk/pull/21216/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21216&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341060
  Stats: 103 lines in 1 file changed: 39 ins; 59 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/21216.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21216/head:pull/21216

PR: https://git.openjdk.org/jdk/pull/21216