rdbms contrib: send conn to _add_metadata_columns (#3011)
rdbms contrib: send conn to _add_metadata_columns (#3011)

Co-authored-by: Dillon Stadther <e4676899097b002b8d809044037857703176db8a@gmail.com>
riga/luigi,spotify/luigi,dlstadther/luigi,riga/luigi,dlstadther/luigi,riga/luigi,riga/luigi,dlstadther/luigi,dlstadther/luigi,spotify/luigi,spotify/luigi,spotify/luigi