RFR: 8356114: java/foreign/TestBufferStackStress2.java failed with junit action timed out [v3]

[Per Minborg]

> This PR proposes to skip a stress test if the `main` thread is a virtual thread.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Cleanup merges

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25084/files
  - new: https://git.openjdk.org/jdk/pull/25084/files/39bbc360..5aeb01af

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25084&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25084&range=01-02

  Stats: 5 lines in 1 file changed: 1 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/25084.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25084/head:pull/25084

PR: https://git.openjdk.org/jdk/pull/25084