glsl: Bump some test timeouts up to 5 minutes.

We're seeing intermittent failures in CI on the qemu-emulated tests on s390x and ppc64, where the test takes >60s instead of 3-5 seconds. Both the groups of tests that fail spawn many GLSL compiler/preprocessor processes, each of which has to spin up qemu.

I'm assuming the failure is bad scheduling when the shared runners are under heavy load and we don't get picked often enough to get the job done. Crank the timeout up a bit to see if that clears it up.