ipatests: fix tasks.wait_for_replication method
    
    With the fix for https://pagure.io/freeipa/issue/9171, the
    method entry.single_value['nsds5replicaupdateinprogress'] now
    returns a Boolean instead of a string "TRUE"/"FALSE".
    
    The method tasks.wait_for_replication needs to be fixed so that
    it properly detects when replication is not done.
    
    Fixes: https://pagure.io/freeipa/issue/9530
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>