[Autofill] Add Autofill StrikeSystem to waterfall testing config

Bug: 884817
Change-Id: Iab61ac0b51d4541313f48263cadbfe2110fac543
Reviewed-on: https://chromium-review.googlesource.com/c/1321255Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Jared Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/master@{#606087}

testing/variations/fieldtrial_testing_config.json

@@ -752,6 +752,25 @@
             ]
         }
     ],
+    "AutofillSaveCreditCardUsesStrikeSystem": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "AutofillSaveCreditCardUsesStrikeSystem"
+                    ]
+                }
+            ]
+        }
+    ],
     "AutofillSingleClick": [
         {
             "platforms": [