22824:add ability to update discount and markup schedules

These parameter appends and the [associated metasql](https://github.com/xtuple/xtuple/pull/1570/files) lead to multiple statements getting executed by a single call to the database server. The error handling that follows won't catch all of the possible errors (e.g. what happens if the second of 3 statements fails but the others succeed?). In addition the work isn't wrapped in a transaction so some rows might be updated and others not.