ci: Bump Clang to 19 for Linux builds, align LLVM repository with runner version (#2844)

* ci: Bump Clang to 19 for Linux builds
* PR #2434 was intended to bump Clang to 19. In reality it only made sure that clang-format-19 is being used and that the shadPS4 codebase can be compiled with Clang 19.
This PR makes sure that Clang 19 is actually being used for Linux builds which makes sense since we use Clang 19 for Windows builds already (Since Visual Studio 17.13 Clang 19 is being shipped).

* ci: Use noble variant of LLVM repository
* shadPS4 has been using Ubuntu 24.04 runners for some time now. This commit makes sure the correct LLVM repository is being used.