[clang-tools-extra] [clangd] [Modules] Fix to correctly handle module dependencies (PR #142828)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

@fleeting-xx BTW, I think this worth to be backported to 20.x. But we need to fix the above problem first.

https://github.com/llvm/llvm-project/pull/142828