MDEV-32515 Use $MYSQLD_LAST_CMD in spider/bugfix.mdev_30370

$MYSQLD_CMD uses .1 as the defaults-group-suffix, which could cause
the use of the default port (3306) or socket, which will fail in
environment where these defaults are already in use by another server.

Adding an extra --defaults-group-suffix=.1.1 does not help, because
the first flag wins.

So we use $MYSQLD_LAST_CMD instead, which uses the correct suffix.

The extra innodb buffer pool warning is irrelevant to the goal of the
test (running --wsrep-recover with --plug-load-add=ha_spider should
not cause hang)

storage/spider/mysql-test/spider/bugfix/r/mdev_30370.result

 #
 # MDEV-30370 mariadbd hangs when running with --wsrep-recover and --plugin-load-add=ha_spider.so
 #
+call mtr.add_suppression(".*\\[Warning\\] InnoDB: Skipping buffer pool dump/restore during wsrep recovery");
 # Kill the server
 # restart
 Warnings:

storage/spider/mysql-test/spider/bugfix/t/mdev_30370.test

@@ -3,10 +3,9 @@
 --echo # MDEV-30370 mariadbd hangs when running with --wsrep-recover and --plugin-load-add=ha_spider.so
 --echo #
 
-let $MYSQLD_DATADIR= `select @@datadir`;
-let $PLUGIN_DIR=`select @@plugin_dir`;
+call mtr.add_suppression(".*\\[Warning\\] InnoDB: Skipping buffer pool dump/restore during wsrep recovery");
 --source include/kill_mysqld.inc
---exec $MYSQLD_CMD --datadir=$MYSQLD_DATADIR --wsrep-recover --plugin-dir=$PLUGIN_DIR --plugin-load-add=ha_spider
+--exec $MYSQLD_LAST_CMD --wsrep-recover --plugin-load-add=ha_spider
 --source include/start_mysqld.inc
 --disable_query_log
 --source ../../include/clean_up_spider.inc