Fix sporadic failure of MTR test galera.galera_many_tables_pk

The test relies on the false assumption that node_1 is always
"assigned" autoincrement value 1 for a given key.
However that is no necessarily the case when wsrep autoincrement
control is enabled.

This patch changed the test so that it does not make use of a
autoincrement key, which is not fundamental for the test itself.

codership/mysql-wsrep#322

mysql-test/suite/galera/t/galera_many_tables_pk.test

@@ -16,7 +16,7 @@
 while ($count)
 {
   --disable_query_log
-  --let $ddl_var = `SELECT CONCAT("CREATE TABLE t", $count, " (f1 INTEGER AUTO_INCREMENT PRIMARY KEY) ENGINE=InnoDB")`
+  --let $ddl_var = `SELECT CONCAT("CREATE TABLE t", $count, " (f1 INTEGER PRIMARY KEY) ENGINE=InnoDB")`
   --eval $ddl_var
   --enable_query_log
   --dec $count
@@ -37,7 +37,7 @@ START TRANSACTION;
 while ($count)
 {
   --disable_query_log
-  --let $ddl_var = `SELECT CONCAT("INSERT INTO t", $count, " VALUES (DEFAULT)")`
+  --let $ddl_var = `SELECT CONCAT("INSERT INTO t", $count, " VALUES (1)")`
   --eval $ddl_var
   --enable_query_log
   --dec $count