[Flang][OpenMP][Driver][Test] Fix the omp-driver-offload-test commands (#66926)

Since the changes to -### to correctly return error codes in D156363,
some additions of the not lit keyword and perhaps some changes to how
fopenmp-targets is handled; the test omp-driver-offload.f90 has become a
little susceptible to what appears to be sporadic failures.

This was because if certain environment variables are set for AMD
devices some of the commands succeed happily and the not check causes
the test to fail. Whereas, if they were not set the tests would fail and
the not test would succeed, allowing the test to pass provided you were
not targeting AMD hardware while running the test.

When the environment variables for AMD hardware are set the compiler
could find the correct offload architecture to compile for, allowing the
command to succeed. However, when not set it'd fail as it can't detect
the offload architecture. The solution to this is to specify an AMD
architecture via --offload-arch so it always passes, the architecture
doesn't really matter, I've chosen to select gfx90a.