[clang] [NFC][clang] Remove superfluous header files after refactor in #132252 (PR #132495)

[Erich Keane via cfe-commits]

erichkeane wrote:

> > How'd you manage to find the right ones? IMO we should be using include-what-you-use on these to make sure we get it right (if you have already, disregard this).
> > Also, can you share before-split/after-split/after-this build time benchmarks? Does this get us back to reasonable?
> 
> There's a clang-tidy rule for this right? I assumed that's what this was.

I'm not aware of a tidy rule that does include-file management, but if so, that is equally as good, if that is what was used.  Just pushing to make sure we get this done in an automated fashion.

https://github.com/llvm/llvm-project/pull/132495