[clangd] Fix a regression in rL366996.

Summary: That patch made the tweak always annotate the whole file by accident.

Reviewers: jvikstrom

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65443

llvm-svn: 367313