[Autofill] Declare profile cleanup field trial groups for testing

testing/variations/fieldtrial_testing_config_linux.json

 {
     "AsyncDNS": [
         {
             "group_name": "AsyncDNSA"
         }
     ],
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
     ],
     "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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     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }