Switch from Android dEQP to Khronos GL CTS.
We now mirror from the public Khronos Github
github.com/KhronosGroup/VK-GL-CTS
This includes a number of text fixes for GLES 2.0 conformance.

Bug: angleproject:3914
Bug: angleproject:1656
Change-Id: I4cccd33e47752742cb989127c5883c0afd075b9e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1879579Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>