remove an extraneous include (#18269)

Signed-off-by: Karl Haubenwallner <[email protected]>

Code/Framework/AzCore/AzCore/Serialization/Json/JsonSerializationMetadata.inl

@@ -59,5 +59,3 @@ namespace AZ
         return const_cast<JsonSerializationMetadata*>(this)->Find<MetadataT>();
     }
 } // namespace AZ
-
-#include <AzCore/Serialization/Json/JsonSerializationMetadata.inl>