Call non_native_setup in scripts that use mysqltest

A few tests didn't call it explicitly and relied on the implicit
initialization that was done in the test driver.

maxscale-system-test/insertstream.sh

@@ -1,3 +1,4 @@
 #!/bin/bash
 
+./non_native_setup insertstream
 ./mysqltest_driver.sh insertstream insertstream 4006

maxscale-system-test/masking_mysqltest_driver.sh

@@ -36,6 +36,10 @@ fi
 
 echo $source copied to $target
 
+test_dir=`pwd`
+
+$test_dir/non_native_setup $1
+
 password=
 if [ $# -ge 3 ]
 then