Skip mariabackup.slave_provision_nolock in --valgrind, it uses a lot of CPU

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

mysql-test/suite/mariabackup/slave_provision_nolock.test

 --source include/have_innodb.inc
 --source include/have_log_bin.inc
+# Test does a lot of queries that take a lot of CPU under Valgrind.
+--source include/not_valgrind.inc
 
 call mtr.add_suppression("Can't init tc log");
 call mtr.add_suppression("Aborting");