Adjust namespaces in the Cache folder

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

src/Umbraco.Infrastructure/Logging/LogHttpRequest.cs

@@ -1,6 +1,5 @@
 using System;
 using Umbraco.Cms.Core.Cache;
-using Umbraco.Core.Cache;
 
 namespace Umbraco.Core.Logging
 {

src/Umbraco.Infrastructure/Logging/Serilog/Enrichers/HttpRequestIdEnricher.cs

@@ -2,7 +2,6 @@
 using Serilog.Core;
 using Serilog.Events;
 using Umbraco.Cms.Core.Cache;
-using Umbraco.Core.Cache;
 
 namespace Umbraco.Core.Logging.Serilog.Enrichers
 {

src/Umbraco.Infrastructure/Logging/Serilog/Enrichers/HttpRequestNumberEnricher.cs

@@ -3,7 +3,6 @@ using System.Threading;
 using Serilog.Core;
 using Serilog.Events;
 using Umbraco.Cms.Core.Cache;
-using Umbraco.Core.Cache;
 
 namespace Umbraco.Core.Logging.Serilog.Enrichers
 {