RFR: 8304437: ProblemList com/sun/jdi/ThreadMemoryLeadTest.java with ZGC

[Chris Plummer]

This new test is failing with ZGC, I believe on every run. Needs to be problem listed.

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Commit messages:
 - ProblemList ThreadMemoryLeakTarg.java

Changes: https://git.openjdk.org/jdk/pull/13087/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13087&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304437
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13087.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/13087/head:pull/13087

PR: https://git.openjdk.org/jdk/pull/13087