tests: fix backup-restore scenario with replica
    
    The test TestBackupAndRestoreWithReplica is simulating a
    master crash in order to check the behavior after ipa-restore.
    
    Since commit 67a33e5, the uninstaller restarts the services in
    order to unregister the server from PKI security domain. An
    indirect consequence is that master/replica communication is re-
    established and operations removing entries (done by the uninstaller)
    are replicated to the replica.
    This means that the scenario does not really simulate a server crash.
    
    To make sure that no replication happens during this "crash", stop
    the replica first, then uninstall the master, and finally restart
    the replica before calling the ipa-restore command on the master.
    
    Fixes: https://pagure.io/freeipa/issue/9404
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>