[clang] [clang-tools-extra] Remove clang-rename (PR #108988)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> can you inspect these files that still reference clang-rename?
> 
> ```
> lib/Tooling/Refactoring/Rename/RenamingAction.cpp:        errs() << "clang-rename: renamed at: " << SourceMgr.getFilename(FullLoc)
> lib/Tooling/Refactoring/Rename/USRFindingAction.cpp:            "clang-rename could not find symbol (offset %0)");
> lib/Tooling/Refactoring/Rename/USRFindingAction.cpp:          DiagnosticsEngine::Error, "clang-rename could not find symbol %0");
> ```

Yeah, those confused me as well -- I think it's just happenstance that it uses `clang-rename` in those strings because as best I can tell, there's no relationship between `clang-rename` and `Tooling/Refactoring/Rename`. CC @hyp who may have more information.

https://github.com/llvm/llvm-project/pull/108988