sysutils/graylog: update to 5.0.2

• support JAVA_HOME
• accept additional java parameters in rc.conf
• OpenJDK17 is now required
• remove unsupported JVM tunables

Reported by: Einar Bjarni Halldórsson <einar@isnic.is>
Differential Revision: https://reviews.freebsd.org/D37979