Enabling the unit tests for SERVER-65364 highlighted that the current detection logic based on diff objects returns a false positive in two situations (i.e. an index is marked as requiring an update even if the change is outside of the indexed paths).

Unit test: UpdateArrayNodeTest.NoArrayElementAffectsIndexes
Index path: a.c
Operation: set a.$[i].b

Unit test: SetNodeTest.ApplySetFieldInNonExistentNumericFieldDoesNotAffectIndexOnSiblingField
Index path: a.1.b
Operation: set a.1.c