Update the testing config with the new experiments for PVer4.

Google CLs: http://cl/137190961, http://cl/137192202

BUG=543161

Review-Url: https://codereview.chromium.org/2450963002
Cr-Commit-Position: refs/heads/master@{#486392}

testing/variations/fieldtrial_testing_config.json

@@ -2848,7 +2848,11 @@
             ],
             "experiments": [
                 {
-                    "name": "Enabled"
+                    "name": "V4Only2",
+                    "enable_features": [
+                        "SafeBrowsingV4LocalDatabaseManagerEnabled",
+                        "SafeBrowsingV4OnlyEnabled"
+                    ]
                 }
             ]
         }