MDEV-20888 : Galera test failure on galera.galera_pc_ignore_sb: 2013: Lost...

MDEV-20888 : Galera test failure on galera.galera_pc_ignore_sb: 2013: Lost connection to MySQL server during query

Add debug info.

mysql-test/suite/galera/t/galera_pc_ignore_sb.cnf

+!include ../galera_2nodes.cnf
+
+[mysqld]
+wsrep_debug=1
+
+[mysqld.1]
+wsrep_provider_options='base_port=@mysqld.1.#galera_port;gcache.size=1;pc.ignore_sb=true'
+
+[mysqld.2]
+wsrep_provider_options='base_port=@mysqld.2.#galera_port;gcache.size=1;pc.ignore_sb=true'
+