RFR: 8364936: Shenandoah: Switch nmethod entry barriers to conc_instruction_and_data_patch [v2]

[Cesar Soares Lucas]

> Hi all,
> 
> This pull request contains a backport of commit [81a1e8e1](https://github.com/openjdk/jdk/commit/81a1e8e1363446de499a59fc706221efde12dd86) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Cesar Soares Lucas on 8 Sep 2025 and was reviewed by Fei Yang, Dingli Zhang, Kelvin Nilsen and William Kemper.
> 
> I had to manually resolve a merge conflict in `TestHotSpotVMConfig.java` because the original patch modified a region of the file that is not present in this repository version of the same file.
> 
> Thanks!

Cesar Soares Lucas has updated the pull request incrementally with one additional commit since the last revision:

  This also needs to be reverted.

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

Changes:
  - all: https://git.openjdk.org/shenandoah-jdk21u/pull/218/files
  - new: https://git.openjdk.org/shenandoah-jdk21u/pull/218/files/49c12b6b..af29f617

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=218&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=218&range=00-01

  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/218.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/218/head:pull/218

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/218