Add title to 'unprovision' dialog
    
    To improve translation quality the title of 'unprovision' dialog
    should be specified explicitly in the spec and should be an entire
    sentence.
    
    Fixes: https://pagure.io/freeipa/issue/7704
    Reviewed-By: Serhii Tsymbaliuk <stsymbal@redhat.com>
    Reviewed-By: Christian Heimes <cheimes@redhat.com>