RFR: 8282384: [LOOM] Need test for ThreadReference.interrupt() on a vthread

[Chris Plummer]

Convert this ThreadReference.interrupt() test to support virtual threads. I believe this is the only test for ThreadReference.interrupt() that we have.

Tested by running with and without -Dmain.wrapper=Virtual on all supported platforms.

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

Commit messages:
 - Add vthread support to interrupt test

Changes: https://git.openjdk.org/jdk/pull/13696/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13696&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8282384
  Stats: 18 lines in 2 files changed: 5 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/13696.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13696/head:pull/13696

PR: https://git.openjdk.org/jdk/pull/13696