Previously replaced ops would have all children with regions marked
as ignored also. This removes that change as it then erroneously ignored
regions that were later moved to other unignored/replaced regions.
This change might hurt performance of the ConversionPatternRewriter
by now checking ancestral ops to see if this op is "dangling" due to
any of those ops being removed, but should not be a driving performance
Note, this is not an NFC optimization removal because now some ops
that were being ignored due to a replace-and-move situation are not
ignored, and additionally, children of replaced ops were previously not
ignored in the optimization scheme but now will be if they are dangling.