RFR: 8340273: Remove CounterHalfLifeTime

[Daniel Lundén]

The CounterHalfLifeTime flag is no longer used and should be removed.

### Changeset

Remove CounterHalfLifeTime.

### Testing

N/A

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

Commit messages:
 - Remove CounterHalfLifeTime

Changes: https://git.openjdk.org/jdk/pull/21034/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21034&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340273
  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21034.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21034/head:pull/21034

PR: https://git.openjdk.org/jdk/pull/21034