Set assistant as a role

- Register a role observer in VoiceInteractionManagerService. Once the
role is changes map the new role setting onto the old settings.
- As the assistant role is now always set, there is no need to have code
in AssistUtil for the case the assistant setting is not set
- Remove old config option for the default assistant. The default
assistant is not configured via the roles config

Bug: 110557011
Test: - Set, unset and swtiched assistant via the settings UI
        - for voice interaction service
	- for assist activity
      - Booted from freshly wiped device and saw assitant to be set to
        default
Change-Id: I8596f49c6f6496e8b70cf3236aaa7d7557443a93
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index cef47ca..279e55e 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -1546,6 +1546,12 @@
                 traceEnd();
             }
 
+            // Grants default permissions and defines roles
+            traceBeginAndSlog("StartRoleManagerService");
+            mSystemServiceManager.startService(new RoleManagerService(
+                    mSystemContext, new LegacyRoleResolutionPolicy(mSystemContext)));
+            traceEnd();
+
             // We need to always start this service, regardless of whether the
             // FEATURE_VOICE_RECOGNIZERS feature is set, because it needs to take care
             // of initializing various settings.  It will internally modify its behavior
@@ -1996,12 +2002,6 @@
             }
             traceEnd();
 
-            // Grants default permissions and defines roles
-            traceBeginAndSlog("StartRoleManagerService");
-            mSystemServiceManager.startService(new RoleManagerService(
-                    mSystemContext, new LegacyRoleResolutionPolicy(mSystemContext)));
-            traceEnd();
-
             // No dependency on Webview preparation in system server. But this should
             // be completed before allowing 3rd party
             final String WEBVIEW_PREPARATION = "WebViewFactoryPreparation";