Re-enable Intel D3D12 Validation Tests

Re-enables Intel D3D12 GPU-based validation bots. This comes after the
--enable-backend-validation=partial option was introduced and the bot
configurations were changed to make use of it.

Bug: dawn:598
Change-Id: I9f5c5111340aeefa729e0d2fd26f9f884813eb3a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/40481
Commit-Queue: Brandon Jones <brandon1.jones@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>

src/tests/DawnTest.cpp

@@ -868,11 +868,6 @@ void DawnTestBase::SetUp() {
         glfwMakeContextCurrent(gTestEnv->GetOpenGLESWindow());
     }
 #endif
-
-    // A very large number of tests hang on Intel D3D12 with the debug adapter after a driver
-    // upgrade. Violently suppress this whole configuration until we figure out what to do.
-    // See https://crbug.com/dawn/598
-    DAWN_SKIP_TEST_IF(IsBackendValidationEnabled() && IsIntel() && IsD3D12());
 }
 
 void DawnTestBase::TearDown() {