Removes the various old hacks for the legacy user's membership provider, now that we have the AllowManuallyChangingPassword flag, these hacks are not required.

src/Umbraco.Web.UI/install/steps/DefaultUser.ascx.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Web.Security;
 using Umbraco.Core.Configuration;
+using Umbraco.Core.Security;
 using Umbraco.Web.Install;
 using Umbraco.Web.Security;
 using umbraco.BusinessLogic;
@@ -60,7 +61,7 @@ namespace Umbraco.Web.UI.Install.Steps
                 }
 
                 // Is it using the default membership provider
-                if (CurrentProvider is UsersMembershipProvider)
+                if (CurrentProvider.IsUmbracoUsersProvider())
                 {
                     // Save user in membership provider
                     var umbracoUser = user as UsersMembershipUser;