[clang] [clang] Update argument checking tablegen code to use a 'full' name (PR #99993)

[Oliver Hunt via cfe-commits]

ojhunt wrote:

@AaronBallman ah with more context, I see we didn't actually land "// Do something if not an identifier" (implying partial commit history at some point". I'm looking at exactly what happens, or if we're missing some test cases -- it's possible that when written there was the intent to either add more similar parameters, do better error checks, or possibly just over engineering. Will need to investigate further to verify, will try to determine the expected behaviour today or tomorrow (I agree if it is not necessary it should be removed - ie. if it was just added "for the future" or similar and it's had quite a few years for that future to happen and not be needed)

https://github.com/llvm/llvm-project/pull/99993