[clangd] Find References shows deleted files

clangd doesn't remove cached data for files deleted while it was disabled.

Steps to reproduce:

1. Enable clangd in options
2. Create new project with main.cpp and OtherClass.h, or clone https://github.com/VolodymyrZibarov/clangdRenameBug.git and open it
3. Find References in OtherClass.h for member "value". It shows 2 files: main.cpp and OtherClass.h, as expected.
4. Disable CLangd in options
5. Rename file OtherClass.h to OtherClass2.h, class name remains unchanged.
6. Enable CLangd in options
7. Find References in OtherClass2.h for member "value".

Expected result:

2 files in results list

Actual result:

3 files in results list, including OtherClass.h, that was renamed: