[GR-49221] Fold thread dump experimental option into enable-monitoring

[galderz]

The option to generate a thread dump is currently experimental, e.g. -H:+DumpThreadStacksOnSignal. Instead it should be folded into the enable-monitoring option.

[fniephaus]

Do you mean a threaddump argument for --enable-monitoring, similar to the heapdump argument?

[fniephaus]

Done via #7612.

[galderz]

Thanks @fniephaus!