MDEV-15351: wsrep_sst_xtrabackup is broken in 10.1.31

Remove the setup_ports function call. This is related to
https://github.com/MariaDB/server/pull/717

Thanks to Daniel Black and Bart S.

scripts/wsrep_sst_xtrabackup.sh

@@ -408,7 +408,6 @@ if [[ ! ${WSREP_SST_OPT_ROLE} == 'joiner' && ! ${WSREP_SST_OPT_ROLE} == 'donor'
 fi
 
 read_cnf
-setup_ports
 get_stream
 get_transfer