Add WebRTC-Video-QualityScaling default experiment config

Bug: chromium:1155063
Change-Id: Ib9180912321b8f5e0d49f8e1cfbda53c47ee0222
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2577219
Auto-Submit: Ilya Nikolaevskiy <ilnik@chromium.org>
Commit-Queue: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835140}

testing/variations/fieldtrial_testing_config.json

@@ -8218,6 +8218,21 @@
             ]
         }
     ],
+    "WebRTC-Video-QualityScaling": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled-29,95,149,205,24,37,26,36,0.9995,0.9999,1"
+                }
+            ]
+        }
+    ],
     "WebRTC-Vp9ExternalRefCtrl": [
         {
             "platforms": [