ipatests: increase timeout for test_trust
    
    The timeout for test_trust is too short (6000s) and
    the nightly tests often fail. Increase to 7200s.
    
    Fixes: https://pagure.io/freeipa/issue/9326
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Anuja More <amore@redhat.com>