Add GeoLanguage in fieldtrial testing

Bug: 76915
Change-Id: Ia0f05256c85eb67daae13c20b96a067a06cfb2ba
Reviewed-on: https://chromium-review.googlesource.com/816574
Commit-Queue: Renjie Liu <renjieliu@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#525216}

testing/variations/fieldtrial_testing_config.json

@@ -1497,6 +1497,25 @@
             ]
         }
     ],
+    "GeoLanguage": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
+                "win"
+            ],
+            "experiments": [
+                {
+                    "name": "GeoLanguage",
+                    "enable_features": [
+                        "GeoLanguage"
+                    ]
+                }
+            ]
+        }
+    ],
     "GoogleBrandedContextMenu": [
         {
             "platforms": [