filters external login providers in the back office to only show the ones configured for umbraco back office

src/Umbraco.Web.UI/umbraco/Views/Default.cshtml

@@ -58,11 +58,11 @@
 
     @{
         var loginProviders = Context.GetOwinContext().Authentication.GetExternalAuthenticationTypes()
+            .Where(p => p.Properties.ContainsKey("UmbracoBackOffice"))
             .Select(p => new
             {
                 authType = p.AuthenticationType,
                 caption = p.Caption,
-                //TODO: Need to see if this exposes any sensitive data!
                 properties = p.Properties
             })
             .ToArray();

src/Umbraco.Web/Editors/BackOfficeController.cs

@@ -395,6 +395,7 @@ namespace Umbraco.Web.Editors
                     {
                         {
                             "providers", HttpContext.GetOwinContext().Authentication.GetExternalAuthenticationTypes()
+                                .Where(p => p.Properties.ContainsKey("UmbracoBackOffice"))
                                 .Select(p => new
                                 {
                                     authType = p.AuthenticationType, caption = p.Caption,