RFR: 8356114: java/foreign/TestBufferStackStress2.java failed with junit action timed out [v2]

[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 two additional commits since the last revision:

 - Update test/jdk/java/foreign/TestBufferStackStress2.java
   
   Co-authored-by: Daniel Jelinski <djelinski1 at gmail.com>
 - Update test/jdk/java/foreign/TestBufferStackStress2.java
   
   Co-authored-by: Daniel Jelinski <djelinski1 at gmail.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25084/files
  - new: https://git.openjdk.org/jdk/pull/25084/files/6ee12db8..39bbc360

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25084&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25084&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 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