Add finch fieldtrial testing config for network time queries

testing/variations/fieldtrial_testing_config_mac.json

 {
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
     ],
     "AutofillFieldMetadata": [
         {
             "group_name": "Enabled"
         }
@@ skipping 115 matching lines @@
     "MaterialDesignDownloads": [
         {
             "group_name": "Enabled"
         }
     ],
     "MojoChannel": [
         {
             "group_name": "Enabled"
         }
     ],
+    "NetworkTimeQueries": [
+        {
+            "enable_features": [
+                "NetworkTimeServiceQuerying"
+            ],
+            "group_name": "NetworkTimeQueriesEnabled"
+        }
+    ],
     "OfferUploadCreditCards": [
         {
             "group_name": "Enabled"
         }
     ],
     "OutOfProcessPac": [
         {
             "group_name": "Enabled"
         }
     ],
@@ skipping 210 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }