RFR: 8313332: Simplify lazy jmethodID cache in InstanceKlass [v2]

[Coleen Phillimore]

> This change simplifies the code that grows the jmethodID cache in InstanceKlass.  Instead of lazily, when there's a rare request for a jmethodID for an obsolete method, the jmethodID cache is grown during the RedefineClasses safepoint.  The InstanceKlass's jmethodID cache is lazily allocated when there's a jmethodID allocated, so not every InstanceKlass has a cache, but the growth now only happens in a safepoint.  This code will become racy with the potential change for deallocating jmethodIDs.
> 
> Tested with tier1-4, vmTestbase/nsk/jvmti java/lang/instrument tests (in case they're not in tier1-4).

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

  Refactoring suggested by Serguei.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18549/files
  - new: https://git.openjdk.org/jdk/pull/18549/files/ffffe38f..6576d14d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18549&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18549&range=00-01

  Stats: 32 lines in 2 files changed: 12 ins; 16 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/18549.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18549/head:pull/18549

PR: https://git.openjdk.org/jdk/pull/18549