Background activity starts are now blocked by default.

Change the default for "Allow background activity starts" to off,
matching the logic in the activity manager.

Bug: 129955487
Bug: 129533810
Test: make RunSettingsRoboTests \
ROBOTEST_FILTER=AllowBackgroundActivityStartsPreferenceControllerTest

Change-Id: If9eeae699f9c8b7913da4456a45286f816cc7463

src/com/android/settings/development/AllowBackgroundActivityStartsPreferenceController.java

@@ -82,10 +82,10 @@ public class AllowBackgroundActivityStartsPreferenceController
 
     private boolean isDefaultEnabled() {
         // The default in the absence of user preference is settable via DeviceConfig.
-        // Note that the default default is enabled.
+        // Note that the default default is disabled.
         return DeviceConfig.getBoolean(
                 DeviceConfig.NAMESPACE_ACTIVITY_MANAGER,
                 KEY_DEFAULT_BACKGROUND_ACTIVITY_STARTS_ENABLED,
-                /*defaultValue*/ true);
+                /*defaultValue*/ false);
     }
 }