New: Speed up API add by reworking SeriesExistsValidator

src/NzbDrone.Core/Validation/Paths/SeriesExistsValidator.cs

@@ -1,4 +1,5 @@
-using System;
+using System;
+using System.Linq;
 using FluentValidation.Validators;
 using NzbDrone.Core.Tv;
 
@@ -24,7 +25,7 @@ namespace NzbDrone.Core.Validation.Paths
 
             var tvdbId = Convert.ToInt32(context.PropertyValue.ToString());
 
-            return !_seriesService.GetAllSeries().Exists(s => s.TvdbId == tvdbId);
+            return !_seriesService.AllSeriesTvdbIds().Any(s => s == tvdbId);
         }
     }
 }