[IMP] http/db: change behaviour of list_dbs() when `--db-filter` is not provided (Closed #18526)

In case `--db-filter` is not provided and `--database` is passed,
Odoo will not fetch the list of databases available in the postgres
server anymore because it does not have anything to match against this
list. Instead, `list_dbs()` will use the value of `--database` as a
comma separated list of exposed databases.

This allows better security hardening in postgres access rights.

Basically, that means that those commands

    $ odoo-bin -d foobar
    $ odoo-bin -d foo,bar,baz

are now respectively equivalent to those commands

    $ odoo-bin -d foobar --db-filter='^foobar$'
    $ odoo-bin -d foo,bar,baz --db-filter='^(foo|bar|baz)$'

The old behaviour can still be used with this command:

    $ odoo-bin -d foobar --db-filter='.*'

0 files changed, 0 insertions, 0 deletions