RFR: 8306733: Remove template paramter of G1DetermineCompactionQueueClosure::free_pinned_region

[Thomas Schatzl]

Hi all,

  after [JDK-8298048](https://bugs.openjdk.org/browse/JDK-8298048) G1DetermineCompactionQueueClosure::free_pinned_region() may only be called with humongous regions, so the template parameter is unnecessary. This PR removes it.
I kept the method itself (not inlined) because I believe its name acts as a good documentation what is done here at the place it is called, even if it's only 3 LOC.

Testing: local compilation, gha

Thanks,
  Thomas

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

Commit messages:
 - After JDK-8298048 G1DetermineCompactionQueueClosure::free_pinned_region() may only be called with humongous regions, so the template parameter is unnecessary.

Changes: https://git.openjdk.org/jdk/pull/13610/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13610&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306733
  Stats: 10 lines in 2 files changed: 0 ins; 6 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/13610.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13610/head:pull/13610

PR: https://git.openjdk.org/jdk/pull/13610