fixes Add class construction on occ when user_ldap is not enabled

[blizzz]

ConnectionImporter depends on LDAP backend's helper class 🙈 and if it cannot be found and instantiated occ breaks with

 php occ status
An unhandled exception has been thrown:
ArgumentCountError: Too few arguments to function OCA\LDAPContactsBackend\Command\Add::__construct(), 0 passed in /srv/http/nextcloud/stable20/lib/private/Console/Application.php on line 224 and exactly 2 expected in /srv/http/nextcloud/master/apps-repos/ldap_contacts_backend/lib/Command/Add.php:46
Stack trace:
#0 /srv/http/nextcloud/stable20/lib/private/Console/Application.php(224): OCA\LDAPContactsBackend\Command\Add->__construct()
#1 /srv/http/nextcloud/stable20/lib/private/Console/Application.php(136): OC\Console\Application->loadCommandsFromInfoXml(Array)
#2 /srv/http/nextcloud/stable20/console.php(99): OC\Console\Application->loadCommands(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#3 /srv/http/nextcloud/stable20/occ(11): require_once('/srv/http/nextc...')

[MorrisJobke]

🐘