Optional packages (e.g. tribol) are always built if +cuda

[Alex Tyler Chapman]

https://github.com/LLNL/serac/blob/develop/scripts/spack/packages/serac/package.py#L236C1-L242C69

    # Check if these variants are true first
    cuda_deps_with_variants = ["raja", "sundials", "tribol", "umpire"]
    for dep in cuda_deps_with_variants:
        depends_on("{0}+cuda".format(dep), when="+cuda") // <-- change this
        for sm_ in CudaPackage.cuda_arch_values:
            depends_on("{0} cuda_arch={1}".format(dep, sm_),
                    when="+{0}+cuda cuda_arch={1}".format(dep, sm_))

depends_on("{0}+cuda".format(dep), when="+cuda") // currently
depends_on("{0}+cuda".format(dep), when="+{0}+cuda") // suggestion

We want to check if these are enabled before building with them.