Cursor fetch synthesizes a ROWSTAT column that pollutes the metadata and reports therefore an additional column. We should strip the column from the metadata. The JDBC driver does this depending on whether a server-side cursor was spun up. Since the cursorId is received in a ReturnValue token which comes last, we cannot wait for the ReturnValue. Instead, we inspect whether the last column is named ROWSTAT and remove it if so.

Related to r2dbc/r2dbc-spi/issues#187.