OOR-CORS: Enable the feature for fieldtrial testing

Tests are already running on Android WebView P OOR-CORS FYI (rel) and
linux-oor-cors-rel fyi bots. But this testing flag flip is also the
best practices that is good to follow.

Bug: 905971, 1001450
Change-Id: I75ccebb1466be8b516f96774ceabb377951d3160
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1882770
Commit-Queue: Ilya Sherman <isherman@chromium.org>
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710078}

testing/variations/fieldtrial_testing_config.json

@@ -4095,6 +4095,26 @@
             ]
         }
     ],
+    "OutOfBlinkCors": [
+        {
+            "platforms": [
+                "android",
+                "android_webview",
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "OutOfBlinkCors"
+                    ]
+                }
+            ]
+        }
+    ],
     "OutOfProcessQuarantine": [
         {
             "platforms": [