RFR: 8320522: Remove code related to `RegisterFinalizersAtInit` [v5]

[Dan Heidinga]

> Remove the code related to -XX:[+-]RegisterFinalizersAtInit in JDK23.
> 
> `make test-tier1` passed with this change

Dan Heidinga has updated the pull request incrementally with one additional commit since the last revision:

  Remove unused variable

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18823/files
  - new: https://git.openjdk.org/jdk/pull/18823/files/0a34511d..741f1250

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18823&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18823&range=03-04

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 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