[clang] [clang-tools-extra] [llvm] [clangd] Avoid bogus error about recursive inclusion (PR #95200)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

The title of the PR can probably be improved. The current title describes the symptom the patch fixes rather than the change it makes (which I don't understand well).

(I changed it from the Phabricator revision's title, which was "[clangd] WIP: fix several bugs relating to include insertion", since I don't think that's accurate any more.)

https://github.com/llvm/llvm-project/pull/95200