Fixed up some errors and do the guid cache fix on the module instead of backend coz that would cause other issues.

(cherry picked from commit 8eaab46488f00a74197c517c6ef773626aec5173)

src/NzbDrone.Core/Indexers/IndexerBase.cs

@@ -79,7 +79,6 @@ namespace NzbDrone.Core.Indexers
 
             result.ForEach(c =>
             {
-                c.Guid = string.Concat(Definition.Id, "_", c.Guid);
                 c.IndexerId = Definition.Id;
                 c.Indexer = Definition.Name;
                 c.DownloadProtocol = Protocol;