jdk19 Jep425Tests_testVirtualThread_0 hangs

[pshipton]

Jep425Tests_testVirtualThread_0 in sanity.functional testing is hanging, on alinux, aix, plinux, xlinux, windows. Not on amac, zlinux, xmac.

This was first seen in PR testing #16002 (comment)
also seen in the OMR acceptance build https://openj9-jenkins.osuosl.org/job/Pipeline-OMR-Acceptance/379/
Did not occur in the nightly build last night https://openj9-jenkins.osuosl.org/job/Pipeline-Build-Test-JDK19/164/

I believe that makes the culprit one of these changes.
cb8605d...02c3cf1

#15968 - PR tested on alinux
#15612 - PR tested on xlinux
#15996 - PR tested on amac, which is a passing platform.

@fengxue-IS @babsingh pls take a look.

[babsingh]

• The hang happens due to Update Continuation.yield to use onPinned API #15996.
• Created Revert "Update Continuation.yield to use onPinned API" #16016 to revert it.
• See javacore; all vthreads and their carrier threads are parked: javacore.20220929.085955.17624.0001.txt.

[pshipton]

As #15996 was reverted after confirming reverting fixes the hang, this issue can be closed.