This switches 'angle_*_tests' to be identical to
'standalone_angle_*_tests'. Once rolled into Chromium we can
then switch back to using 'angle_*_tests' and finally remove
'standalone_angle_*_tests' entirely.

Must land after https://crrev.com/c/2490987

Bug: angleproject:5124
Change-Id: I1f4794d429733a43113dcba6aaaba0c047607e50
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2491932Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>