Revert "Enable GpuWatchdogV2 in Field trial testing for all platforms"

This reverts commit 752f7f2c.

Reason for revert: <Watchdog V2 causes crashes in the bots and it falls back to SwiftShader. bug 995372>

Original change's description:
> Enable GpuWatchdogV2 in Field trial testing for all platforms
> 
> Bug: 949839
> Change-Id: I5939069144719c501209af3cda3b7693f61f8866
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1682315
> Commit-Queue: Maggie Chen <magchen@chromium.org>
> Reviewed-by: Ilya Sherman <isherman@chromium.org>
> Reviewed-by: Zhenyao Mo <zmo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#688375}

TBR=isherman@chromium.org,zmo@chromium.org,magchen@chromium.org

Change-Id: I2f64da411b2289265c1a9657fae85c083953bfb8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 949839
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1761559Reviewed-by: Maggie Chen <magchen@chromium.org>
Commit-Queue: Maggie Chen <magchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688690}

testing/variations/fieldtrial_testing_config.json

@@ -2546,25 +2546,6 @@
             ]
         }
     ],
-    "GpuWatchdogV2": [
-        {
-            "platforms": [
-                "android",
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "GpuWatchdogV2"
-                    ]
-                }
-            ]
-        }
-    ],
     "GridLayoutForNtpShortcuts": [
         {
             "platforms": [