Skip "SplitChunks "Phase of Collection Defragmentation if featureFlagNoMoreAutoSplitter is enabled

The final phase of the collection defragmentation algorithm introduced in v5.3 generates a sequence of autoSplitVector & splitChunk commands to guarantee the "maxChunkSize" constraint on all the chunks of the collection.

Such constraint is no more present in v6.x (as a consequence of activating the "no more autosplitter" feature).