Enable JVM Heap trimming by default

@maxandersen and @franz1981 taught me java 17 has support for jvm reclaiming memory back to the os:

• https://bugs.openjdk.org/browse/JDK-8293114 this is the feature
• this is what we have for G1 instead: https://bugs.openjdk.org/browse/JDK-8204089

And Netty behaviour is what's missing from the puzzle (see https://github.com/netty/netty/discussions/11845#discussion-3690282)

Meaning that while idle, https://bugs.openjdk.org/browse/JDK-8204089 just shrink back the heap RSS to xms

we need 2 set of VM args to be passed:

• autotrim interval -> which requires something like -XX:+UnlockExperimentalVMOptions -XX:TrimNativeHeapInterval=5000
• G1 periodic GC: -> G1PeriodicGCInterval, G1PeriodicGCInvokesConcurrent and G1PeriodicGCSystemLoadThreshold (for https://bugs.openjdk.org/browse/JDK-8204089)

OpenJDK supports -XX:+IgnoreUnrecognizedVMOptions, in case users run an older JDK 17 that doesn't support the new flags, and OpenJ9 simply ignores unknown flags, so it's probably safe to try it out on insider builds.

@rgrunber @testforstephen @jdneo WDYT?

Examinez comment l’extension transmet les arguments JVM au serveur de langage Java, puis comparez les flags demandés avec OpenJDK JDK-8293114 et JDK-8204089 ainsi qu’avec la discussion Netty référencée. Le travail est terminé lorsque les options de réduction du heap et de GC périodique de G1 sont activées par défaut, tout en préservant le comportement avec les anciennes versions de JDK 17 et OpenJ9.