RFR: 8374233: Overloaded constructor MountUnmountDisabler(jthread thread) is missed

[Serguei Spitsyn]

Please, review a simple fix for a jdk 26 regression: [JDK-8364343](https://bugs.openjdk.org/browse/JDK-8364343). It will be pushed to 27 first and then back ported to 26.
This issue impacts JVM TI scalability. The  [JDK-8364343](https://bugs.openjdk.org/browse/JDK-8364343) replaced the overloaded ctor `MountUnmountDisabler(jthread thread)` with `MountUnmountDisabler(oop thread_oop)`. This caused the most common JVM TI pattern `MountUnmountDisabler disabler(thread)` (where thread is a jthread) to be resolved to `MountUnmountDisabler(bool exclusive)`.  It makes the instantiated `MountUnmountDisabler` to disable `mount/unmount` transitions for all virtual thread instead of the specific one. This problem was identified with a minor tracing.

The fix restores the original ctor `MountUnmountDisabler(jthread thread)`.

Testing:
 - TBD: run mach5 tiers 1-6

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Commit messages:
 - 8374233: Overloaded constructor MountUnmountDisabler(jthread thread) is missed

Changes: https://git.openjdk.org/jdk/pull/28965/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28965&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374233
  Stats: 9 lines in 2 files changed: 9 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28965.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28965/head:pull/28965

PR: https://git.openjdk.org/jdk/pull/28965