769504a ipa_backup.py: replace /var/lib/ipa/backup with paths.IPA_BACKUP_DIR

Authored and Committed by François Cami 4 years ago
    ipa_backup.py: replace /var/lib/ipa/backup with paths.IPA_BACKUP_DIR
    
    /var/lib/ipa/backup is defined in ipaplatform.paths as paths.IPA_BACKUP_DIR
    Remove all instances of /var/lib/ipa/backup/ in ipa_backup.py.
    
    Signed-off-by: François Cami <fcami@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>