This reverts commit 15c7d0a6.

Reason for revert: This change mixed with enabling the depth/stencil backbuffer here: https://chromium-review.googlesource.com/c/angle/angle/+/976339 causes the tests to fail. I will revert these for now and put it back in a new CL once I find the fix instead.

Original change's description:
> Vulkan: Enable depth and stencil dEQP tests
> 
> This enables these tests for Vulkan:
> dEQP-GLES2.functional.fragment_ops.depth.*
> dEQP-GLES2.functional.fragment_ops.stencil.*
> 
> Bug: angleproject:2430
> 
> Change-Id: I5c58821ac2f84ce9ae5a92b3024853e5b85ad41e
> Reviewed-on: https://chromium-review.googlesource.com/981999
> Commit-Queue: Luc Ferron <lucferron@chromium.org>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>

TBR=geofflang@chromium.org,jmadill@chromium.org,lucferron@chromium.org

Change-Id: Ifeebd078c1cc70d90ea1923257777f711c13593e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: angleproject:2430
Reviewed-on: https://chromium-review.googlesource.com/982132Reviewed-by: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Luc Ferron <lucferron@chromium.org>