RFR: 8320522: Remove code related to `RegisterFinalizersAtInit`

[Dan Heidinga]

Remove the code related to -XX:[+-]RegisterFinalizersAtInit in JDK23.

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Commit messages:
 - 8320522: Remove code related to `RegisterFinalizersAtInit`

Changes: https://git.openjdk.org/jdk/pull/18823/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18823&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320522
  Stats: 16 lines in 8 files changed: 0 ins; 11 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/18823.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18823/head:pull/18823

PR: https://git.openjdk.org/jdk/pull/18823