RFR: 8341273: JVMTI is not properly hiding some continuation related methods

[Serguei Spitsyn]

This fixes a problem in the VTMS (Virtual Thread Mount State) transition frames hiding mechanism.
Please, see a fix description in the first comment.

Testing:
 - Verified with new test `vthread/CheckHiddenFrames`
 - Mach5 tiers 1-6 are passed

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

Commit messages:
 - fix one more place with trailing spaces
 - fix trailing spaces
 - add new test coverage with  vthread/CheckHiddenFrames
 - 8341273: JVMTI is not properly hiding some continuation related methods

Changes: https://git.openjdk.org/jdk/pull/21397/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21397&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341273
  Stats: 233 lines in 7 files changed: 210 ins; 7 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/21397.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21397/head:pull/21397

PR: https://git.openjdk.org/jdk/pull/21397