This reverts commit 3d544fff.

Reason for revert: Seems like flakiness is not related.

Suppress D3D11 test failures uncovered by re-enabling D3D debug device:
ComputeShaderTest.DispatchCompute
Texture2DTestES3.TextureImplPropogatesDirtyBits
D3DTextureTestMS.*

Also a small fix to ANGLETestBase::checkD3D11SDKLayersMessages
to clear reported messages, otherwise the failures are also reported
for tests following the one with the actual failure.

Original change's description:
> Temporarily disable creating D3D debug device.
>
> To diagnose whether Windows Intel end2end tests flakiness
> is related to creating debug device and new version of Windows SDK.
>
> Bug: angleproject:3153
> Change-Id: Ica7eae3fe875e22203b6dfd98b83604d66a97737
> Reviewed-on: https://chromium-review.googlesource.com/c/1476954
> Reviewed-by: Geoff Lang <geofflang@chromium.org>
> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>

Bug: angleproject:3153, angleproject:3493
Bug: angleproject:3501, angleproject:3512, angleproject:3513

Change-Id: I232da72aa09c2b9230cf179dd54e1731f8365f8e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1480854Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>