Migrate relevant services to the split swh db create / swh db init

Since swh.core 0.3.0, the database creation (superuser) and database
initialization (user) operations have been split for databases managed using raw
SQL.

• Override the postgresql containers for these services to avoid creating an

empty database.

• Add an entry for the template1 database to .pgpass so other containers can

connect to it

• extend wait_pgsql to take a database name as first argument