[Password Manager] Switch password manager code to use the Feature framework.

testing/variations/fieldtrial_testing_config_ios.json

 {
+    "AffiliationBasedMatching": [
+        {
+            "group_name": "Disabled",
+            "params": {
+                "propagate_password_changes_to_web": "Disabled"
+            }
+        }
+    ],
     "AutofillFieldMetadata": [
         {
             "group_name": "Enabled"
         }
     ],
     "AutofillProfileOrderByFrecency": [
         {
             "group_name": "EnabledLimitTo3",
             "params": {
                 "limit": "3"
             }
         },
         {
             "group_name": "Enabled"
         }
     ],
+    "AutofillSyncCredential": [
+        {
+            "group_name": "DisallowSyncCredentials"
+        },
+        {
+            "group_name": "DisallowSyncCredentialsForReauth"
+        }
+    ],
     "ChromotingQUIC": [
         {
             "group_name": "Enabled"
         }
     ],
     "DataCompressionProxyDevRollout": [
         {
             "group_name": "Control"
         },
         {
@@ skipping 11 matching lines @@
     "PageRevisitInstrumentation": [
         {
             "group_name": "Enabled"
         }
     ],
     "PasswordBranding": [
         {
             "group_name": "SmartLockBrandingSavePromptOnly"
         }
     ],
+    "PasswordManagerDropSyncCredential": [
+        {
+            "group_name": "Enabled"
+        },
+        {
+            "group_name": "Disabled"
+        }
+    ],
     "QUIC": [
         {
             "group_name": "Enabled",
             "params": {
                 "alternate_protocol_probability_threshold": "0.001"
             }
         }
     ],
     "SdchPersistence": [
         {
@@ skipping 20 matching lines @@
     ],
     "VarationsServiceControl": [
         {
             "group_name": "Interval_30min",
             "params": {
                 "fetch_period_min": "30"
             }
         }
     ]
 }