RFR: 8309542: compiler/jvmci/TestEnableJVMCIProduct.java fails with "JVMCI compiler 'graal' specified by jvmci.Compiler not found"

[Doug Simon]

This PR fixes an intermittent failure in TestEnableJVMCIProduct.java that can happen when execution is slow enough such that a top-tier JIT compilation is scheduled.

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Commit messages:
 - let exit value determine what output to check for

Changes: https://git.openjdk.org/jdk/pull/14336/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14336&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309542
  Stats: 10 lines in 1 file changed: 6 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14336.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14336/head:pull/14336

PR: https://git.openjdk.org/jdk/pull/14336