[Templates] Adjust _Imports include condition (#4329)

* Fix Client projects in Web App templates

* Alter _Imports include condition

Author: vnbaaij

src/Templates/templates/blazorweb-csharp-10/BlazorWebCSharp.1/Components/_Imports.razor

@@ -14,6 +14,8 @@
 @using BlazorWebCSharp._1
 @*#if (UseWebAssembly) -->
 @using BlazorWebCSharp._1.Client
+##endif*@
+@*#if (UseWebAssembly && SampleContent) -->
 @using BlazorWebCSharp._1.Client.Layout
 ##endif*@
 @using BlazorWebCSharp._1.Components