[clang] [AMDGPU] Remove detection of hip runtime for Spack (PR #133263)

[Harmen Stoppels via cfe-commits]

haampie wrote:

I believe Spack sets either `HIP_PATH` or `ROCM_PATH` for clang which is considered before the auto-detection removed in this PR.

https://github.com/llvm/llvm-project/pull/133263