RFR: 8339701: Test TestPinCaseWithCFLH.java fails with -Xcomp

[SendaoYan]

Hi all,
  The newly added testcase `serviceability/jvmti/vthread/TestPinCaseWithCFLH/TestPinCaseWithCFLH.java` fails with `-Xcomp` jvm option. The jvm option `-Xcomp` will make `BackgroundCompilation` false. In this test, disable `BackgroundCompilation` will make `instrumentation` in `premain` throw `java.util.MissingResourceException` in some test  environments.
   So, I think it's necessary add `-XX:+BackgroundCompilation` option for this test to make this test more robustness, to make this test run passed with `-Xcomp` option.
  Test-fix only, no risk.

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Commit messages:
 - 8339701: Test TestPinCaseWithCFLH.java fails with -Xcomp

Changes: https://git.openjdk.org/jdk/pull/20906/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20906&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339701
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/20906.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20906/head:pull/20906

PR: https://git.openjdk.org/jdk/pull/20906