RFR: 8319338: tools/jpackage/share/RuntimeImageTest.java fails with -XX:+UseZGC

[Alexey Semenyuk]

Remove `-Xmx512m` from the jtreg `@run` command as @AlanBateman suggested

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Commit messages:
 - 8319338: tools/jpackage/share/RuntimeImageTest.java fails with -XX:+UseZGC

Changes: https://git.openjdk.org/jdk/pull/16535/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16535&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319338
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16535.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16535/head:pull/16535

PR: https://git.openjdk.org/jdk/pull/16535