Provide angle_unittests_run independent of archive_gpu_tests.

https://codereview.chromium.org/457813002/ moved a bunch of tests running
on the GPU waterfalls only behind archive_gpu_tests.  However,
angle_unittests runs on some non-GPU bots (and should run on many more to
prevent issues like crbug.com/487341) and having angle_unittests_run be
available unconditionally is a prerequisite for running them on swarming,
which I'm doing in https://codereview.chromium.org/1690463003/.

The try bots no longer build 'all', so the archive_gpu_tests thing is less
important; also angle_unittests_run takes just 2 seconds to run on my laptop.

BUG= 98637,401985

Review URL: https://codereview.chromium.org/1697843002

Cr-Commit-Position: refs/heads/master@{#375373}
1 file changed