FCBIS restarts the storage engine several times and this can impact marker truncation since swapping out the engine under the oplog cap maintainer thread can result in the collectionMarkers thinking the _intialSamplingFinished flag is never set , and prevent new truncation markers from being created even after initial sampling is complete.

The approach to resolve this is to stop the cap maintainer thread from running whenever we switch out the storage engine as part of FCBIS and restart it once we have reinitialised the engine.