[llvm] [LoopUnroll] Remove redundant debug instructions after blocks have been merged (PR #91246)

[via llvm-commits]

================
@@ -0,0 +1,45 @@
+; RUN: opt < %s -S -passes=loop-unroll | FileCheck %s
----------------
coderchenlin wrote:

Thanks, I use update_test_checks.py to generate CHECKs, and keep some important contents

https://github.com/llvm/llvm-project/pull/91246