[clang] [Sema] [Modules] Remove unrelated module partitions from suggestion list (PR #187657)

[Chuanqi Xu via cfe-commits]

https://github.com/ChuanqiXu9 commented:

Before looking into the changes, I am surprised that: is it supported to suggest module names after import? @mikomikotaishi what's your setup? I don't remember we had support for it.

Would you still see the suggestions if clean your build dir? If no, then may be it is supported implicitly by loading the BMI in the build dir. This is not strictly desired. To support this properly, I think we need to offer information to SemaCodeComplete in clangd.

https://github.com/llvm/llvm-project/pull/187657