[clang] [clang-format] Limit how much work guessLanguage() can do (PR #78925)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> I've merged #82957.

Thanks. I've written the clangd patch and posted it for review at https://github.com/llvm/llvm-project/pull/84133.

If that gets approved, I will abandon this PR.

https://github.com/llvm/llvm-project/pull/78925