Remove flags for controlling credit card scanner.

testing/variations/fieldtrial_testing_config_android.json

 {
     "AllBookmarks": [
         {
             "disable_features": [
                 "AllBookmarks"
             ],
             "group_name": "Disabled"
         }
     ],
     "AndroidSessionNotifications": [
@@ skipping 44 matching lines @@
         }
     ],
     "ContextualSearch": [
         {
             "group_name": "OptOut",
             "params": {
                 "enabled": "true"
             }
         }
     ],
-    "CreditCardScan": [

[Ilya Sherman, 2016/08/03 01:15:03]

Hmm, was the code to query this field trial state already removed in a previous
CL?

-        {
-            "group_name": "Enabled"
-        }
-    ],
     "DataCompressionProxyDevRollout": [
         {
             "group_name": "Control"
         },
         {
             "group_name": "Enabled"
         }
     ],
     "DataCompressionProxyLoFi": [
         {
@@ skipping 501 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }