This is the following of the refactoring initialized in T2736/D4377 with the scheduler.
The database creation is delegated to the postgresql container, and the service database is initialized via the `swh db init-admin` command.i
I have created only one diff instead of one per service to simplify the review.
storage: let postgresql initialize the db and use the swh db init-admin command
scheduler: remove PG* variable from the db configuration
vault: let postgresql initialize the db and use the swh db init-admin command
deposit: let postgresql initialize the db
vault: let postgresql initialize the db and use the swh db init-admin command
listers: let postgresql initialize the db and use the swh db init-admin command