Change tests to use 2.0 templates until SDK is updated

Author: SteveSandersonMS

test/Templates.Test/Helpers/TemplatePackageInstaller.cs

@@ -15,7 +15,6 @@ internal static class TemplatePackageInstaller
             "Microsoft.DotNet.Web.Client.ItemTemplates",
             "Microsoft.DotNet.Web.ItemTemplates",
             "Microsoft.DotNet.Web.ProjectTemplates.2.0",
-            "Microsoft.DotNet.Web.ProjectTemplates.2.1",
             "Microsoft.DotNet.Web.Spa.ProjectTemplates",
             "Microsoft.AspNetCore.SpaTemplates",
         };