OVN NB & SB DB's should be run in separate ovsdb-server processes
and should run with ovn-ctl start_northd / stop_northd. This patch
includes changes to unit tests, tutorial and debian scripts to remain
self-consistent.
Signed-off-by: RYAN D. MOATS <rmoats@us.ibm.com> Signed-off-by: Michael Arnaldi <arnaldimichael@gmail.com> Co-authored-by: Michael Arnaldi <arnaldimichael@gmail.com> Signed-off-by: Russell Bryant <russell@ovn.org>