[clang] [NFC][Driver] Use global --implicit-check-not=libclang_rt (PR #121081)

[Vitaly Buka via cfe-commits]

vitalybuka wrote:

> We should avoid FILECHECK_OPTS. Consider using lit's `DEFINE:` feature.

Done https://github.com/llvm/llvm-project/pull/121159
Also extracted unrelated #121160

https://github.com/llvm/llvm-project/pull/121081