logstash7: Fix passthru.tests since -oss variant removal

{ elk7Version

{ config

, elk7Version

, enableUnfree ? true

, lib

, stdenv

      maintainers = with maintainers; [ wjlroe offline basvandijk ];

    };

    passthru.tests =

      optionalAttrs (!enableUnfree) (

        assert this.drvPath == nixosTests.elk.ELK-7.elkPackages.logstash.drvPath;

      optionalAttrs (config.allowUnfree && enableUnfree) (

        assert this.drvPath == nixosTests.elk.unfree.ELK-7.elkPackages.logstash.drvPath;

        {

          elk = nixosTests.elk.ELK-7;

          elk = nixosTests.elk.unfree.ELK-7;

        }

      );

  };