MDEV-17848: Galera test failure on galera_sst_xtrabackup-v2[_data_dir]

The mariabackup SST script was incorrectly processes
innodb_data_home_dir parameter if it is specified in
the configuration file for one of the cluster nodes.
Therefore, a corresponding revision of the mariabackup
SST script was made, which provides reading of the
corresponding parameter from the configuration file
or from the command line.

https://jira.mariadb.org/browse/MDEV-17848

scripts/wsrep_sst_mariabackup.sh

@@ -678,6 +678,30 @@ fi
 
 INNOEXTRA=""
 
+INNODB_DATA_HOME_DIR=${INNODB_DATA_HOME_DIR:-""}
+# Try to set INNODB_DATA_HOME_DIR from the command line:
+if [ ! -z "$INNODB_DATA_HOME_DIR_ARG" ]; then
+    INNODB_DATA_HOME_DIR=$INNODB_DATA_HOME_DIR_ARG
+fi
+# if INNODB_DATA_HOME_DIR env. variable is not set, try to get it from my.cnf
+if [ -z "$INNODB_DATA_HOME_DIR" ]; then
+    INNODB_DATA_HOME_DIR=$(parse_cnf mysqld$WSREP_SST_OPT_SUFFIX_VALUE innodb-data-home-dir '')
+fi
+if [ -z "$INNODB_DATA_HOME_DIR" ]; then
+    INNODB_DATA_HOME_DIR=$(parse_cnf --mysqld innodb-data-home-dir "")
+fi
+if [ ! -z "$INNODB_DATA_HOME_DIR" ]; then
+   INNOEXTRA+=" --innodb-data-home-dir=$INNODB_DATA_HOME_DIR"
+fi
+
+if [ -n "$INNODB_DATA_HOME_DIR" ]; then
+    # handle both relative and absolute paths
+    INNODB_DATA_HOME_DIR=$(cd $DATA; mkdir -p "$INNODB_DATA_HOME_DIR"; cd $INNODB_DATA_HOME_DIR; pwd -P)
+else
+    # default to datadir
+    INNODB_DATA_HOME_DIR=$(cd $DATA; pwd -P)
+fi
+
 if [[ $ssyslog -eq 1 ]];then 
 
     if ! command -v logger >/dev/null;then
@@ -698,13 +722,13 @@ if [[ $ssyslog -eq 1 ]];then
             logger  -p daemon.info -t ${ssystag}wsrep-sst-$WSREP_SST_OPT_ROLE "$@" 
         }
 
-        INNOAPPLY="${INNOBACKUPEX_BIN} --innobackupex $disver $iapts --apply-log \$rebuildcmd \${DATA} 2>&1  | logger -p daemon.err -t ${ssystag}innobackupex-apply "
+        INNOAPPLY="${INNOBACKUPEX_BIN} --innobackupex $disver $iapts \$INNOEXTRA --apply-log \$rebuildcmd \${DATA} 2>&1  | logger -p daemon.err -t ${ssystag}innobackupex-apply "
         INNOMOVE="${INNOBACKUPEX_BIN} --innobackupex ${WSREP_SST_OPT_CONF} $disver $impts  --move-back --force-non-empty-directories \${DATA} 2>&1 | logger -p daemon.err -t ${ssystag}innobackupex-move "
         INNOBACKUP="${INNOBACKUPEX_BIN} --innobackupex ${WSREP_SST_OPT_CONF} $disver $iopts \$tmpopts \$INNOEXTRA --galera-info --stream=\$sfmt \$itmpdir 2> >(logger -p daemon.err -t ${ssystag}innobackupex-backup)"
     fi
 
 else 
-    INNOAPPLY="${INNOBACKUPEX_BIN} --innobackupex $disver $iapts --apply-log \$rebuildcmd \${DATA} &>\${DATA}/innobackup.prepare.log"
+    INNOAPPLY="${INNOBACKUPEX_BIN} --innobackupex $disver $iapts \$INNOEXTRA --apply-log \$rebuildcmd \${DATA} &>\${DATA}/innobackup.prepare.log"
     INNOMOVE="${INNOBACKUPEX_BIN} --innobackupex ${WSREP_SST_OPT_CONF} $disver $impts  --move-back --force-non-empty-directories \${DATA} &>\${DATA}/innobackup.move.log"
     INNOBACKUP="${INNOBACKUPEX_BIN} --innobackupex ${WSREP_SST_OPT_CONF} $disver $iopts \$tmpopts \$INNOEXTRA --galera-info --stream=\$sfmt \$itmpdir 2>\${DATA}/innobackup.backup.log"
 fi
@@ -847,7 +871,7 @@ then
     [[ -e $SST_PROGRESS_FILE ]] && wsrep_log_info "Stale sst_in_progress file: $SST_PROGRESS_FILE"
     [[ -n $SST_PROGRESS_FILE ]] && touch $SST_PROGRESS_FILE
 
-    ib_home_dir=$(parse_cnf mysqld innodb-data-home-dir "")
+    ib_home_dir=$INNODB_DATA_HOME_DIR
     ib_log_dir=$(parse_cnf mysqld innodb-log-group-home-dir "")
     ib_undo_dir=$(parse_cnf mysqld innodb-undo-directory "")