EES-4670 Remove code that isn't used after DataSetFileMeta migration

Author: mmyoungman

src/GovUk.Education.ExploreEducationStatistics.Common/Converters/GeographicLevelsListJsonConverter.cs

@@ -36,8 +36,7 @@ public override void WriteJson(JsonWriter writer, IList<GeographicLevel>? value,
         while (reader.Read() && reader.TokenType == JsonToken.String)
         {
             var value = (string)reader.Value;
-            var geographicLevel = geographicLevels.First(gl => gl.GetEnumValue() == value
-                                                               || gl.GetEnumLabel() == value); // EES-4670 Can be removed after migration done in EES-5140
+            var geographicLevel = geographicLevels.First(gl => gl.GetEnumValue() == value);
             result.Add(geographicLevel);
         }