RFR: 8338603: DiagnosticCommandMBean operations should standardize types for parameters

[Kevin Walls]

DiagnosticCommandImpl should only publish parameter types in a known standard set, and use "STRING" on anything else.
e.g. We can say "FILE" in the help output for jcmd, as that's for humans, but the MBean parameter info should contain "STRING".

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Commit messages:
 - Test update
 - 8338603: DiagnosticCommandMBean operations should standardize types for parameters.

Changes: https://git.openjdk.org/jdk/pull/21040/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21040&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338603
  Stats: 57 lines in 2 files changed: 49 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/21040.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21040/head:pull/21040

PR: https://git.openjdk.org/jdk/pull/21040