Deprecate the check if a JVMTI collector is present assertion

When the heap sampler was added, a lot of various paths could lead to where the allocation could happen and it was not trivial to see if a collector was present.

Since then, a refactor took place and the code actually has merged all paths to a single memAllocator path that then does the collection and allocation in the same spot.

Therefore, the assertion code is no longer needed.

Furthermore, it is a nop right now, it basically says:
   Say there is a collector
   Check if there is a collector
   Say there is no longer a collector

And there is no path that would not make both statements not true.