Each user of the original value is modified in-place. Therefore, the corresponding notification should be triggered. This simplifies the GreedyPatternRewriteDriver: it does not care about op replacements, but only about which ops were modified so that they can be put on the worklist. (We still listen for replacement notifications for better debug messages.)
Also fixes a bug where `RewriterBase::mergeBlocks` did not notify the GreedyPatternRewriteDriver when replacing uses of block arguments. This function does not trigger an "operation replaced" notifications, so the GreedyPatternRewriteDriver was not made aware of such IR changes.
Depends On: D144547