Filter based on columns declared in TabletMetadataCheck

[keith-turner]

In #5247 a new interface was introduced for atomically checking tablet metadata to see if a tablet metadata could be updated. This interface allows declaring columns that should be read for the check. Currently in the code nothing is done with those columns and all the tablet columns are read. The code should be updated to only read the requested columns to avoid parsing unneeded data and loading it into memory for the check.