Kill off admin/config.sh, moving it instead into DBDefs like everything else. (MBS-7619)

Just a bit of a pet peeve of mine, though it'll also be useful for potentially removing the gap in replication packets issue when data dumps happen, and is definitely useful when it comes to schema change testing. Speaking of which, I tested this using rika's still-extant schema 20 master, from which it successfully exported a replication packet (or, at least, as successfully as it did before this change).