sporadic failures of galera.galera_sst_mariabackup

the test failed almost always in release (but not in debug) builds with

--- galera_sst_mariabackup.result
+++ galera_sst_mariabackup.reject
@@ -5,7 +5,7 @@
 connection node_1;
 select @@innodb_undo_tablespaces;
 @@innodb_undo_tablespaces
-0
+3
 connection node_2;
 select @@innodb_undo_tablespaces;
 @@innodb_undo_tablespaces

and

[Warning] InnoDB: Cannot change innodb_undo_tablespaces=0 because previous shutdown was not with innodb_fast_shutdown=0

because mariadbd *before this test* wasn't using innodb_fast_shutdown=0

Fix the bootstrap to use innodb_fast_shutdown=0 (and the bootstrap
creates a starting point for any test that uses a .cnf file)

followup for cac0fc97cc

also, remove redundant include/have_innodb.inc

mysql-test/include/galera_cluster.inc

@@ -13,10 +13,8 @@ if (!$galera_cluster_size)
 }
 
 --source include/galera_init.inc
---source include/have_innodb.inc
 --source include/galera_wait_ready.inc
 
-
 --let $_galera_node= $galera_cluster_size
 
 while ($_galera_node != 1)