ci: Enable GLES3 testing on db410c/db820c (freedreno a306 and a530).
We haven't had it enabled due tointermittent failures. Those failures
are, as far as I can tell, due to GPU faults from buffer overflows where a
failing test in a thread stomps an otherwise passing thread's buffers. By
running deqp single-threaded, we can get more consistent failures, at the
cost of needing to do a tiny subset of the tests to keep runtime down.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4685>