Expand position check test and fix for other unit systems

[amandalund]

See #1094.

[sethrj]

Thanks!

[sethrj]

I think the CI is borking the ROCm jobs that are on hardware:

unknown file: Failure
C++ exception with description "/var/jenkins/workspace/celeritas_PR-1097/src/corecel/sys/KernelAttributes.hh:75:
celeritas: device error: hipFuncGetAttributes(&attr, reinterpret_cast<void const*>(func)) failed:
    shared object initialization failed" thrown in the test body.