Some of the valid instants in MDT are ignored

We do have some special instants times like initialization instant times, compaction, clean etc in MDT timeline. 

During InstantRange check, these should be considered as valid. Especially with MDT partition initialization, the suffix is dynamic, and so we can't really find exact match.So, might have to go with total instant time length and treat all special instant times as valid ones. 

In the LogRecordReader, we will first ignore any uncommitted instants. And then if its completed in MDT timeline, we check w/ the instantRange. and so its should be fine to return true for any special instant times.