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 cac0fc97

also, remove redundant include/have_innodb.inc