Audit VM shutdown procedure to reliably create a VM snapshot

[ThanHenderson]

While testing VM snapshotting on a JDK:

openjdk version "25-internal" 2025-09-16
OpenJDK Runtime Environment (build 25-internal-adhoc.root.rel)
Eclipse OpenJ9 VM (build master-f806233768, JRE 25 Linux amd64-64-Bit Compressed References 20241230_000000 (JIT enabled, AOT enabled)
OpenJ9   - f806233768
OMR      - 7af9de5d5
JCL      - ccbec431ad0 based on jdk-25+2)

freeJavaVM does not get called during protectedDestroyJavaVM. Rather, this path is always taken. This prevents a VM snapshot from being created and persisted to disk because the creation paths are in freeJavaVM which is called later in that function.

I know this behaviour begins to happen between JDK 21 (which I have tested and it does not happen) and the build above. i.e. I am unsure if it also affects JDK23 since I haven't gotten to testing that yet.