Gatherer: make UniqueDbnamesListingMaintainer more passive
Gatherer: make UniqueDbnamesListingMaintainer more passive

Run only 1x per day and sleep 1min between tables. Could currently cause some
load on weaker machines.

cybertec-postgresql/pgwatch2,cybertec-postgresql/pgwatch2,cybertec-postgresql/pgwatch2,cybertec-postgresql/pgwatch2