RFR: JDK-8292064 Convert java/lang/management/MemoryMXBean shell tests to java version

[Bill Huang]

This task converts 5 shell tests below to java version. 
test/java/lang/management/MemoryMXBean/LowMemoryTest2.sh 
test/java/lang/management/MemoryMXBean/MemoryManagementParallelGC.sh 
test/java/lang/management/MemoryMXBean/MemoryManagementSerialGC.sh 
test/java/lang/management/MemoryMXBean/MemoryTestAllGC.sh 
test/java/lang/management/MemoryMXBean/PendingAllGC.sh

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Commit messages:
 - Removed othervm option in Pending.java.
 - Converted MemoryMXBean shell tests to java version.

Changes: https://git.openjdk.org/jdk/pull/9813/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9813&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292064
  Stats: 356 lines in 9 files changed: 48 ins; 303 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/9813.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9813/head:pull/9813

PR: https://git.openjdk.org/jdk/pull/9813