[jdk21u-dev] RFR: 8338314: JFR: Split JFRCheckpoint VM operation

[Satyen Subramaniam]

Backporting JDK-8338314: JFR: Split JFRCheckpoint VM operation. This change adds more detail to JFR logging in the hs_err to help with debugging. Ran GHA Sanity Checks, and local Tier 1, and Tier 2 tests. Patch is clean.

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Commit messages:
 - Backport 6d430f24df9d599fe1e12c6b65117c02773ae5d8

Changes: https://git.openjdk.org/jdk21u-dev/pull/1494/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1494&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338314
  Stats: 23 lines in 3 files changed: 12 ins; 1 del; 10 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1494.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1494/head:pull/1494

PR: https://git.openjdk.org/jdk21u-dev/pull/1494