Removed the inserts from the test. They don't make any functional
difference and it only slows the whole system down.
Also reduced the number of threads doing the change user command. This
should reduce the CPU usage of the test.
See script directory for method. The script to run in the top level
MaxScale directory is called maxscale-uncrustify.sh, which uses
another script, list-src, from the same directory (so you need to set
your PATH). The uncrustify version was 0.66.
The test unnecessarily did an unconditional drop of the user resulting in
errors. Also prevented stopping of MaxScale if it wasn't started in the
first place.
