Adjust namespaces in the Cache folder

I made these Umbraco.Cms.Core even though they have to reside in infrastructure.

src/Umbraco.Infrastructure/Cache/RepositoryCachePolicyBase.cs

@@ -1,11 +1,13 @@
-using System;
+// Copyright (c) Umbraco.
+// See LICENSE for more details.
+
+using System;
 using System.Collections.Generic;
-using Umbraco.Cms.Core.Cache;
 using Umbraco.Cms.Core.Models.Entities;
 using Umbraco.Cms.Core.Scoping;
 using Umbraco.Core.Scoping;
 
-namespace Umbraco.Core.Cache
+namespace Umbraco.Cms.Core.Cache
 {
     /// <summary>
     /// A base class for repository cache policies.