RFR: 8316967: Correct the scope of vmtimer in UnregisteredClasses::load_class [v3]

[Calvin Cheung]

> Simple fix for removing the vmtimer from `UnregisteredClasses::load_class` and the corresponding `PerfClassTraceTime` constructor.
> 
> Passed tier1 testing.
> --------------------
> Update: correct the scope of the vmtimer instead of removing it.

Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:

  use perf_app_classload_time

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16046/files
  - new: https://git.openjdk.org/jdk/pull/16046/files/321bde57..fd2a078b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16046&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16046&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16046.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16046/head:pull/16046

PR: https://git.openjdk.org/jdk/pull/16046