Revert "Run WebGL 2.0 conformance tests against Viz changes."

This reverts commit 3cb37960.

Reason for revert: there are a high volume of changes in this subdirectory right now, causing overloading of the GPU bots.

Bug: 848084, 843290
No-Try: True
Tbr: fsamuel@chromium.org
Tbr: danakj@chromium.org
Tbr: samans@chromium.org
Tbr: sadrul@chromium.org

Original change's description:
> Run WebGL 2.0 conformance tests against Viz changes.
> 
> This will increase the likelihood that intermittent failures caused by
> changes in this directory will be caught on the commit queue.
> 
> Bug: 843290
> Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
> Change-Id: Ie4d230c0290706c956d88f483b82b98f3a62f4bf
> Reviewed-on: https://chromium-review.googlesource.com/1069598
> Reviewed-by: Fady Samuel <fsamuel@chromium.org>
> Commit-Queue: Kenneth Russell <kbr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#560799}

TBR=kbr@chromium.org,fsamuel@chromium.org,samans@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 843290
Change-Id: Id5dddfac8e7cdb271628de739e8179459b368c49
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/1080075Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563098}

components/viz/PRESUBMIT.py

@@ -19,10 +19,9 @@ def PostUploadHook(cl, change, output_api):
   """git cl upload will call this hook after the issue is created/modified.
 
   This hook modifies the CL description in order to run extra GPU
-  tests (in particular, the WebGL 2.0 conformance tests) in addition
-  to the regular CQ try bots. This test suite is too large to run
-  against all Chromium commits, but should be run against changes
-  likely to affect these tests.
+  tests (in particular, on Android) in addition to the regular CQ try
+  bots. These tests don't yet run by default on
+  android_n5x_swarming_rel, but viz changes need to run them.
 
   When adding/removing tests here, ensure that both gpu/PRESUBMIT.py and
   ui/gl/PRESUBMIT.py are updated.
@@ -30,9 +29,6 @@ def PostUploadHook(cl, change, output_api):
   return output_api.EnsureCQIncludeTrybotsAreAdded(
     cl,
     [
-      'luci.chromium.try:linux_optional_gpu_tests_rel',
-      'luci.chromium.try:mac_optional_gpu_tests_rel',
-      'luci.chromium.try:win_optional_gpu_tests_rel',
       'luci.chromium.try:android_optional_gpu_tests_rel',
     ],
     'Automatically added optional GPU tests to run on CQ.')