fix(postgres): Support setting the database name via the infrastructure config.

The PostgreSQL client previously assembled a DSN without a database name, leaving connections to fall back on the server-side default (typically the username). This change reads the new databaseName field from the Fairway PostgreSQL dependency proto and encodes it as the URL path, so the resulting DSN takes the form postgres://user:pass@host:port/dbname.

The Fairway proto field previously named name has been renamed to clientName upstream to disambiguate it from the new databaseName field. This MR bumps the fairway dependency to v1.15.1 and updates the accessor accordingly (pg.GetName() → pg.GetClientName()).

Issue: gitlab-com/gl-infra/platform/runway/team#873 (closed)