Fix authorization setup in Razor pages template (#23029)

Author: captainsafia

src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Startup.cs

@@ -109,12 +109,11 @@ public void ConfigureServices(IServiceCollection services)
 #endif
 #if (OrganizationalAuth)
 
-            services.AddRazorPages().AddMvcOptions(options =>
+            services.AddRazorPages();
+            services.AddAuthorization(options =>
             {
-                var policy = new AuthorizationPolicyBuilder()
-                    .RequireAuthenticatedUser()
-                    .Build();
-                options.Filters.Add(new AuthorizeFilter(policy));
+                // By default, all incoming requests will be authorized according to the default policy
+                options.FallbackPolicy = options.DefaultPolicy;
             });
 #else
             services.AddRazorPages();