Before this change, uninitialized databases would be initialized with the old
schema and then migrated to the latest version. After this change, unintialized
databases are initizialized with the latest database schema immediately, without
having to run any of the migrations. This change has no effect on existing
databases.
Before this change, Postgres database initialization was done manually using
utils/psqlinit.sh. This is inconsistent with SQLite, which the bot initializes
itself. It also requires shell access to the server running the Postgres
instance, which means it cannot be used on managed Postgres instances. After
this change, the bot initializes Postgres databases as it does with SQLite, and
utils/psqlinit.sh has been removed as it is now unecessary.
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