[AF] Remove fieldtrial config for AutofillCreditCardAuthentication

Change-Id: I474e8993f701227990db31aa825aa1c73345394e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2542662Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Jared Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/master@{#828490}

testing/variations/fieldtrial_testing_config.json

@@ -720,22 +720,6 @@
             ]
         }
     ],
-    "AutofillCreditCardAuthentication": [
-        {
-            "platforms": [
-                "android",
-                "android_webview"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "AutofillCreditCardAuthentication"
-                    ]
-                }
-            ]
-        }
-    ],
     "AutofillEnableCardNicknameManagementAndUpstream": [
         {
             "platforms": [