Fixes U4-1479 by adding .ToList() to allowed templates, which ensures that the list is fetched from the database while the connection is still open.

Fixing typo in usage of LogHelper in PhysicalFileSystem.
Ensures connection is closed after using TableExists for MySql.
Adds logging to UmbracoDatabase.

src/Umbraco.Core/IO/PhysicalFileSystem.cs

@@ -147,7 +147,7 @@ namespace Umbraco.Core.IO
             }
             catch (FileNotFoundException ex)
             {
-                LogHelper.Info<PublishingStrategy>(string.Format("DeleteFile failed with FileNotFoundException: {0}", ex.InnerException));
+                LogHelper.Info<PhysicalFileSystem>(string.Format("DeleteFile failed with FileNotFoundException: {0}", ex.InnerException));
             }
         }