[jdk11u-dev] RFR: 8278115: gc/stress/gclocker/TestGCLockerWithSerial.java has duplicate -Xmx

[Aleksey Shipilev]

Test backport to improve testing. Does not apply cleanly, because the test have not been moved in the separate package (done in bulk later).

Additional testing:
 - [x] Linux x86_64 fastdebug, affected test still passes

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Commit messages:
 - Backport 0fbd2713f1b47c343172fa34be021706c957520e

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/727/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=727&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278115
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/727.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/727/head:pull/727

PR: https://git.openjdk.java.net/jdk11u-dev/pull/727