test/random.jl: segregate deterministic tests at the end

See https://github.com/JuliaLang/julia/issues/8313 for context and in particular https://github.com/JuliaLang/julia/issues/8313#issuecomment-55493151 for the rationale of this change.
In short, the first test in "test/random.jl", which needed to seed the global RNG with a deterministic value (`srand(0)`), was leaking determinism on all the tests coming after it.
I'm not sure why you would like seeding with a `rand(Uint)`... is it so to be able to print only an `Uint` instead of `RANDOM_SEED` which is an array of four `Uint32` ?