Merge branch 'ldap_user_filter_update2' into 'master' [ci skip]

Remove `memberOf` OID in LDAP `user_filter` docs

While not technically invalid, it is not necessary to have the 
`memberOf` OID in the `user_filter`. It clutters things up and causes
confusion for users so it's better if we remove it from the docs.

See merge request !7809