[clang-tidy] RenamerClangTidy wont emit fixes in scratch space

Prevent fixes being displayed if usages are found in the scratch buffer.
See [[ https://bugs.llvm.org/show_bug.cgi?id=46219 | Fix-It hints are being generated in the ScratchBuffer ]].
It may be wise down the line to put in a general fix in clang-tidy to prevent ScratchBuffer replacements being applied, but for now this will help.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D82162