RFR: 8343931: Removed unused code in CompressedKlassPointers::initialize_for_given_encoding

[Albert Mingkun Yang]

Trivial removing dead code.

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

Commit messages:
 - trivial

Changes: https://git.openjdk.org/jdk/pull/22007/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22007&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343931
  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22007.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22007/head:pull/22007

PR: https://git.openjdk.org/jdk/pull/22007