remove '-u root' from create_user*.sh

Call of MariaDB client from local machine with sudo with '-u root' parameter
does not work with 10.4

maxscale-system-test/create_user.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-mysql -u root --force $1 <<EOF >& /dev/null
+mysql --force $1 <<EOF >& /dev/null
 
 DROP USER IF EXISTS '$node_user'@'%';
 CREATE USER '$node_user'@'%' IDENTIFIED BY '$node_password';

maxscale-system-test/create_user_galera.sh

@@ -4,14 +4,14 @@
 
 for ((i=0;i<100;i++))
 do
-    mysql -ss -u root $1 -e 'show status like "wsrep_ready"' | grep 'ON' && break || sleep 1
+    mysql -ss $1 -e 'show status like "wsrep_ready"' | grep 'ON' && break || sleep 1
 done
 
 # The removal of the anonymous ''@'localhost' user is done in a somewhat crude
 # way. The proper way would be to do a secure installation or drop the users
 # with DROP USER statements.
 
-mysql -u root --force <<EOF
+mysql --force <<EOF
 
 DELETE FROM mysql.user WHERE user = '';