ClearTest.ChangeFramebufferAttachmentFromRGBAtoRGB/ES2_OpenGL

Fails on AMD and all vendors.

Bug: angleproject:5165
Change-Id: Id98c14a695cd9b3dd0c5f57d77932908833f9406
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2468357Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Ian Elliott <ianelliott@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>