[ENH]: Pathfinder CI test case coverage improvements

cuda.pathfinder is currently tested in CI for two CTK installation modes: a system CTK and one whose components are individually provided via wheels. Generally, pathfinder seems to be tested wherever cuda.bindings and cuda.core are tested.

Instead, cuda.pathfinder ought to have its own matrix of CI jobs that test the four installation modes that are supported: a system install, a wheel install, a conda install, and a local install of the ctk at a nonstandard directory the user points to via CUDA_HOME.

The solution might look like removing the pathfinder tests from the existing jobs and assigning a dedicated CI workflow to pathfinder that runs pathfinder tests across all the CTK installation modes. Existing testing coverage of cuda-core and cuda-bindings could be maintained if desired.