[cuda.compute]: add CI jobs that test the `sysctk` and `minimal-sysctk` extras

By default cupy does not pip install the cuda toolkit (unless the `[ctk]` extra is specified), so we should use the `sysctk` extra in that situation, and make sure that we test it in our CI. Additionally, our `sysctk` extra currently pulls in the ctk through numba-cuda, so we need to adjust the definition of the extra to not do that, by simply removing the `[cu12]`/`[cu13]` extra