[clang] [clang-tools-extra] [lldb] [llvm] [mlir] Remove unused variables in the monorepo (PR #204994)

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

@DavidSpickett Do you think the CI failures are releated? (They're all timeouts AFAICT)

https://github.com/llvm/llvm-project/pull/204994