RFR: 8346886: Add since checker test to jdk.management.jfr

[Nizar Benalla]

Please review this patch to add a new test to check `@since` tags in the `jdk.management.jfr` module.

TIA

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Commit messages:
 - add new `@since` test

Changes: https://git.openjdk.org/jdk/pull/25612/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25612&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346886
  Stats: 30 lines in 1 file changed: 30 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/25612.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25612/head:pull/25612

PR: https://git.openjdk.org/jdk/pull/25612