Enable more detailed GC logs including safepoint logging, assign PULSAR_GC

[lhotari]

• safepoint logging will reveal how long it takes to reach safepoints. more details: https://blanco.io/blog/jvm-safepoint-pauses/

• Java 11 uses a newer syntax to enable safepoint logging with Xlog parameter

  • blog post explaining the syntax of the Xlog parameter: https://blog.arkey.fr/2020/07/28/embracing-jvm-unified-logging-jep-158-jep-271/

• remove PULSAR_GC_LOG workaround

• assign PULSAR_GC to -XX:+UseG1GC -XX:MaxGCPauseMillis=10

[yabinmeng]

LGTM