RFR: 8327729: Remove deprecated xxxObject methods from jdk.internal.misc.Unsafe [v2]

[Eirik Bjørsnøs]

> Please review this PR which removes the 19 deprecated `xxObject*` alias methods from `jdk.internal.misc.Unsafe`.
> 
> These methods were added in JDK-8213043 (JDK 12), presumably to allow `jsr166.jar` to be used across JDK versions. This was a follow-up fix after JDK-8207146 had renamed these methods to `xxReference*'.
> 
> Since OpenJDK is now the single source of truth for `java.util.concurrent`, time has come to remove these deprecated alias methods.
> 
> This change was initially discussed here: https://mail.openjdk.org/pipermail/core-libs-dev/2024-March/119993.html
> 
> Testing: This is a pure deletion of deprecated methods, so the PR includes no test changes and the `noreg-cleanup` label is added in the JBS. I have verified that all `test/jdk/java/util/concurrent/*` tests pass.
> 
> Tagging @DougLea and @Martin-Buchholz to verify that this removal is timely.

Eirik Bjørsnøs has updated the pull request incrementally with one additional commit since the last revision:

  Use getAndSetReference instead of getAndSetObject in test/hotspot/jtreg/gc/shenandoah/compiler/TestUnsafeLoadStoreMergedHeapStableTests.java

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18176/files
  - new: https://git.openjdk.org/jdk/pull/18176/files/997056d5..a333ed30

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18176&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18176&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18176.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18176/head:pull/18176

PR: https://git.openjdk.org/jdk/pull/18176