[VectorCombine] foldSelectShuffle - remove extra adds of old shuffles to worklist (llvm#127999)

We already push the old shuffles to the worklist as part of the replaceValue calls, so we shouldn't need to add them to the deferred list as well - my guess is this was to ensure that the instructions got erased first to help cleanup unused instructions, but eraseInstruction should handle this now.

Author: RKSimon

llvm/lib/Transforms/Vectorize/VectorCombine.cpp

@@ -3036,8 +3036,6 @@ bool VectorCombine::foldSelectShuffle(Instruction &I, bool FromReduction) {
   Worklist.pushValue(NSV0B);
   Worklist.pushValue(NSV1A);
   Worklist.pushValue(NSV1B);
-  for (auto *S : Shuffles)
-    Worklist.add(S);
   return true;
 }