updated to use constant

src/Umbraco.Core/Configuration/UmbracoSettings/UserProviderElement.cs

@@ -12,7 +12,7 @@ namespace Umbraco.Core.Configuration.UmbracoSettings
                 return new OptionalInnerTextConfigurationElement<string>(
                       (InnerTextConfigurationElement<string>)this["DefaultBackofficeProvider"],
                     //set the default
-                      "UsersMembershipProvider");
+                      Constants.Conventions.User.UmbracoUsersProviderName);
             }
         }
 

src/Umbraco.Tests/Configurations/UmbracoSettings/ProvidersElementTests.cs

@@ -1,4 +1,5 @@
 using NUnit.Framework;
+using Umbraco.Core;
 
 namespace Umbraco.Tests.Configurations.UmbracoSettings
 {
@@ -8,7 +9,7 @@ namespace Umbraco.Tests.Configurations.UmbracoSettings
         [Test]
         public void Users()
         {
-            Assert.IsTrue(SettingsSection.Providers.DefaultBackOfficeUserProvider == "UsersMembershipProvider");
+            Assert.IsTrue(SettingsSection.Providers.DefaultBackOfficeUserProvider == Constants.Conventions.User.UmbracoUsersProviderName);
         }
     }
 }