failover: make sure we switch to anoter server if only port differs
    
    This is a regression introduced in 735af71a8e169f17fa5462db610a1567c9618e29.
    After this commit we checked only server name instead of name and port combo.
    
    Steps to reproduce:
    1. Configure SSSD to use two servers with same name but different ports
    ```
    [domain/LDAP]
    debug_level=0xFFF0
    id_provider = ldap
    ldap_uri = ldap://$SERVER1:12345,ldap://$SERVER1:389
    ldap_tls_cacertdir = /etc/openldap/certs
    ldap_search_base = dc=example,dc=com
    ```
    
    2. The first server port is unreachable, the second is working.
    3. Run sssd and try to resolve user.
    4. Without the patch SSSD tries to connect to the first server twice
       because new URI is not constructed and goes offline.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/4112
    
    Reviewed-by: Michal Židek <mzidek@redhat.com>