[Autofill] Declare profile cleanup field trial groups for testing

testing/variations/fieldtrial_testing_config_ios.json

 {
     "AutofillFieldMetadata": [
         {
             "group_name": "Enabled"
         }
     ],
+    "AutofillProfileCleanup": [
+        {
+            "enable_features": [
+                "AutofillProfileCleanup"
+            ],
+            "group_name": "Enabled"
+        }
+    ],
     "AutofillProfileOrderByFrecency": [
         {
             "group_name": "EnabledLimitTo3",
             "params": {
                 "limit": "3"
             }
         },
         {
             "group_name": "Enabled"
         }
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     ],
     "VarationsServiceControl": [
         {
             "group_name": "Interval_30min",
             "params": {
                 "fetch_period_min": "30"
             }
         }
     ]
 }