[llvm] [BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (PR #89069)

[via llvm-commits]

coderchenlin wrote:

@fhahn , thanks for the review, the title and the PR description has been updated. <br>I'm not very sure the case is necessary, because it's not about any optimization passes, I strongly believe it won't have any bad impact if the  "RemoveRedundantDbgInstrs" is ok. For another reason, I want to add the **c** case to check compile-time, but it seems not appropriate to add into the directory **llvm/test/**

https://github.com/llvm/llvm-project/pull/89069