[jdk26] RFR: 8373627: assert(!is_vthread_transition_disabler()) failed: no suspend allowed for vthread transition disablers

[Serguei Spitsyn]

Please, review a jdk 26 regression backport. This pull request contains a clean backport of simple changeset https://github.com/openjdk/jdk/commit/53ebcdbd029a1c78f8429574b78cecce70c11af2 from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
This changeset was reviewed by [Patricio Chilano Mateo](https://openjdk.org/census#pchilanomate) and [David Holmes](https://openjdk.org/census#dholmes).
I've changed the bug priority to P3 as it is a regression in jdk 26. Should I request a release team approval?

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

Commit messages:
 - Backport 53ebcdbd029a1c78f8429574b78cecce70c11af2

Changes: https://git.openjdk.org/jdk/pull/28860/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28860&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373627
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28860.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28860/head:pull/28860

PR: https://git.openjdk.org/jdk/pull/28860