Additional MT protection
- There can be multiple thinning services in RAWtoALL, change the mutex here to be static to cover them all.
- The thinning service and monitoring both make use of the same underlying (singleton) thread-hostile legacy trigger navigation tool. !40884 (merged) reduced the number of issues, but did not eliminate them.
This MR serialises all legacy HLT monitoring and thinning.
It reduces the frequency of MT-crashes, but still does not eliminate them. A x3 follow up will still be needed.