VisibililtyIterator: Leave the columns referencing a valid table.
Even if the VisibilityIteratorImpl2 is already at the end of
the of the subchunks for a given chunk, leave the columns referencing
the chunk table just in case a TVI might still want to access metadata
from this VisibilityIteratorImpl2.
Cherry-pick from CAS-13437 into CAS-13502