Restrict autocompletion also based on the phonebook known users

apps/dav/appinfo/v1/caldav.php

apps/dav/appinfo/v1/carddav.php

apps/dav/lib/CardDAV/SystemAddressbook.php

apps/dav/lib/Command/CreateCalendar.php

apps/dav/lib/Connector/Sabre/Principal.php

apps/dav/lib/RootCollection.php

apps/dav/tests/unit/CalDAV/AbstractCalDavBackend.php

apps/dav/tests/unit/CardDAV/CardDavBackendTest.php

apps/dav/tests/unit/Connector/Sabre/PrincipalTest.php

apps/files_versions/lib/AppInfo/Application.php

lib/private/Collaboration/Collaborators/MailPlugin.php

lib/private/Collaboration/Collaborators/UserPlugin.php

lib/private/Contacts/ContactsMenu/ContactsStore.php

lib/private/Share20/Manager.php

lib/public/Share/IManager.php

tests/lib/Collaboration/Collaborators/MailPluginTest.php

tests/lib/Collaboration/Collaborators/UserPluginTest.php

tests/lib/Contacts/ContactsMenu/ContactsStoreTest.php