MDEV-15351: wsrep_sst_xtrabackup is broken in 10.1.31

Remove the setup_ports function call. This is related to
#717

Thanks to Daniel Black and Bart S.

Author: Jan Lindström

scripts/wsrep_sst_xtrabackup.sh

@@ -394,7 +394,6 @@ if [[ ! ${WSREP_SST_OPT_ROLE} == 'joiner' && ! ${WSREP_SST_OPT_ROLE} == 'donor'
 fi
 
 read_cnf
-setup_ports
 get_stream
 get_transfer