packaging: enable Parallel Collector GC for management server (#4407)

The default GC algorithm G1 that is enabled by default with Java11
serves well on multiprocessor machines with large amount of memory where
GC is probablistic with low pauses, where response time is more
important than throughput and GC is kept shorter.

The CloudStack management server is largely a multi-threaded server
application that handles and orchestrates several network requests, and
has the default max. heap size of only 2G that can be considered a
small/medium application from a heap size perspective. Perhaps a more
aggresive GC algorithm such as ParallelGC as used in Java8 and before
(that is previous CloudStack releases) would serve better for throughput
and cause more aggresive GC.

Reference: https://docs.oracle.com/en/java/javase/11/gctuning/available-collectors.html#GUID-13943556-F521-4287-AAAA-AE5DE68777CD

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Author: yadvr

packaging/systemd/cloudstack-management.default

@@ -15,7 +15,7 @@
 # specific language governing permissions and limitations
 # under the License.
 
-JAVA_OPTS="-Djava.security.properties=/etc/cloudstack/management/java.security.ciphers -Djava.awt.headless=true -Dcom.sun.management.jmxremote=false -Xmx2G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/var/log/cloudstack/management/ -XX:ErrorFile=/var/log/cloudstack/management/cloudstack-management.err "
+JAVA_OPTS="-Djava.security.properties=/etc/cloudstack/management/java.security.ciphers -Djava.awt.headless=true -Dcom.sun.management.jmxremote=false -Xmx2G -XX:+UseParallelGC -XX:MaxGCPauseMillis=500 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/var/log/cloudstack/management/ -XX:ErrorFile=/var/log/cloudstack/management/cloudstack-management.err "
 
 CLASSPATH="/usr/share/cloudstack-management/lib/*:/etc/cloudstack/management:/usr/share/cloudstack-common:/usr/share/cloudstack-management/setup:/usr/share/cloudstack-management:/usr/share/java/mysql-connector-java.jar"