Summary:
Since each ShadowViewNodePair will point to any matched pair in the "other" tree during diffing, we can rely on the presence of the "other" pointer instead of
always removing nodes from `deletionCreationCandidatePairs` when they're matched.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D28003335
fbshipit-source-id: 0b886946eedc497091ca79c436f160b3d4bf3f1e