RFR: 8329488: Move OopStorage code from safepoint cleanup and remove safepoint cleanup code

[Coleen Phillimore]

This patch gives the ServiceThread a periodic wakeup (same as GuaranteedSafepointInterval) to check if it needs to clean out OopStorage blocks, and move the triggering of this cleaning out of the safepoint cleanup tasks.  Since ICBuffer, StringTable and SymbolTable rehashing have moved, there's nothing that actually triggers the nop safepoint to do cleaning (except SafepointALot), so the OopStorage cleanup won't be triggered.

With moving all of these out of the safepoint cleanup tasks, we can remove the code that sets up multiple threads to do safepoint cleanup.  We can also remove the JFR events and logging that times safepoint cleanup, and a logging test.

Tested with tier1-4.

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Commit messages:
 - Add some timing to control oopstorage cleanup.
 - Remove SafepointCleanup tasks, events and logging.
 - Move OopStorage work to periodic service thread intervals.

Changes: https://git.openjdk.org/jdk/pull/18375/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18375&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329488
  Stats: 287 lines in 14 files changed: 10 ins; 234 del; 43 mod
  Patch: https://git.openjdk.org/jdk/pull/18375.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18375/head:pull/18375

PR: https://git.openjdk.org/jdk/pull/18375