RFR: 8325872: Make GuaranteedSafepointInterval default 0 [v3]

[Coleen Phillimore]

> This change keeps the GuaranteedSafepointInterval option for use with -XX:+HandshakeALot and -XX:+SafepointALot and removes it from working with the MonitorDeflationThread.  The MonitorDeflation thread has it's own timers and doesn't require safepoint to trigger anymore, so the GuaranteedSafepointInterval is logically unrelated except for historical reasons.
> The option AsyncDeflationInterval default is 250 so was used anyway in this code for the monitor deflation thread timer.
> 
> Tested with tier1-8.  Also performance tested this which didn't show any improvements.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Update handshake_or_safepoint_alot comment.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18820/files
  - new: https://git.openjdk.org/jdk/pull/18820/files/4501dc02..2f1a7671

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18820&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18820&range=01-02

  Stats: 6 lines in 1 file changed: 1 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/18820.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18820/head:pull/18820

PR: https://git.openjdk.org/jdk/pull/18820