[llvm] [LV][NFC] Remove remaining uses of undef in tests (PR #169357)

[Florian Hahn via llvm-commits]

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@@ -169,49 +169,3 @@ loop:
 exit:
   ret void
 }
-
-; Make sure we do not crash when the stride is undef.
-define void @stride_undef(ptr %dst) mustprogress {
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fhahn wrote:

just to note, poison stride already check above.

https://github.com/llvm/llvm-project/pull/169357