freedreno/ci: add nightly freedreno gl testing on a750
freedreno/ci: abort a750 testing when a hang is detected
There's no point continuing just to get a massive number of fails.
freedreno/ci: add nightly freedreno gl testing on a750
Not very stable (got a hang 7/20 times while stress-testing), but it's
probably still useful in nightly, especially given how quick it is.
@robclark recently merged gl support (!31534 (merged)) so let's make sure it works and doesn't regress unnoticed