Set back AttachCurrentThread in jvm.cpp

[piiertho]

In #659 we had to change AttachCurrentThread to AttachCurrentThreadAsDaemon in order to be able to close JVM.
This is due to godotengine/godot#95809.
We need to revert this once fixed.

[CedNaru]

This issue has been solved on Godot's master branch. It should also be cherry-picked for Godot 4.3.1, so we can revert that change with the next Godot release.
Here the PR solving it: godotengine/godot#96760
I extensively tested the branch, I couldn't prevent the JVM shutting down anymore.