RFR: 8288474: Move EventContinuationFreezeOld from try_freeze_fast to freeze_slow

[Coleen Phillimore]

This moves the event ContinuationFreezeOld to freeze_slow so it's reported on the different paths to freeze_slow, and renames the events Continuation*Old/Continuation*Slow and Continuation*Young/Continuation*Fast to reflect that they're on the fast/slow paths.  I turned on CONT_JFR and fixed some bugs and turned it back off again.  Some output:

$ jfr summary hotspot-pid-31671-id-1-2022_09_13_19_42_01.jfr | grep Continuation
 jdk.ContinuationThaw                    12193        211929
 jdk.ContinuationThawFast                10139        165420
 jdk.ContinuationFreeze                   3196         57135
 jdk.ContinuationFreezeFast               2788         46397
 jdk.ContinuationThawSlow                 2054         28543
 jdk.ContinuationFreezeSlow                408          5688

Tested locally and with tier7 which seems to run JFR tests.

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Commit messages:
 - Turn off CONT_JFR
 - 8288474: Move EventContinuationFreezeOld from try_freeze_fast to freeze_slow

Changes: https://git.openjdk.org/jdk/pull/10254/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10254&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288474
  Stats: 42 lines in 4 files changed: 9 ins; 8 del; 25 mod
  Patch: https://git.openjdk.org/jdk/pull/10254.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10254/head:pull/10254

PR: https://git.openjdk.org/jdk/pull/10254