The vm.defmeth stress tests should use 
`TestThreadFactory.newThread()`
to start virtual threads if test thread factory is used.
            
`TestThreadFactory.newThread()`
to start virtual threads if test thread factory is used.
- links to
- 
                     Review(master)
        openjdk/jdk/28048 Review(master)
        openjdk/jdk/28048
 P4
  P4