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?

检查扩展如何将 JVM 参数传递给 Java language server，然后将请求的 flags 与 OpenJDK JDK-8293114 和 JDK-8204089 以及所引用的 Netty 讨论进行比较。完成标准是默认启用 heap-trimming 和 G1 周期性 GC 选项，同时保留在较旧 JDK 17 版本和 OpenJ9 上的行为。