Don't serve angular static files in dev mode (#12885)

Don't serve angular static files in dev mode

Author: ryanbrandenburg

src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Startup.cs

@@ -88,7 +88,10 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
 
 #endif
             app.UseStaticFiles();
-            app.UseSpaStaticFiles();
+            if (!env.IsDevelopment())
+            {
+                app.UseSpaStaticFiles();
+            }
 
             app.UseRouting();