In order to reduce the noise in the JDK21 CI, I'm ProblemListing:

    serviceability/sa/UniqueVtableTest.java

on all platforms. Based on [~amenkov]'s analysis in the bug report,
I think it's just pure luck that the recent failures have been on only
macosx-x64 and windows-x64 and NOT on macosx-aarch64.

It looks like [~amenkov] has uncovered a problem that extends to
more than just this test so I'm expanding the existing ProblemListing
in order to give him time to work the bigger issue.