A recent change(s) eliminated the crash that was occuring with the
KHR-GLES3.copy_tex_image_conversions.required.* and
KHR-GLES3.copy_tex_image_conversions.forbidden.* tests.

The still-failing tests are getting 2 types of Vulkan validation errors.

1) The "required" tests get errors about using the VK_FORMAT_R8G8B8A8_UNORM
descriptor-set format when an SINT/UINT component type is required.

2) The "forbidden" tests are getting errors about using more valid memory
objects than allowed.

Bug: angleproject:3458
Bug: angleproject:3800
Change-Id: I9536da6a2c888413ba0ab789a4dc9559d40fcf1b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754391Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Ian Elliott <ianelliott@google.com>
Commit-Queue: Ian Elliott <ianelliott@google.com>