Changes

drop config.vty tests from make check

The intention of those tests was to test various osmo-hnbgw startup
scenarios. It seemed the fastest/simplest way to do it at the time, but
the output depends on another library, regularly causing test fallout.

Keep the tests around for reference. They can still be invoked manually
with 'make config-tests'.

Related: OS#6380
Change-Id: I9c1540904b13d25db1c7933a88f6cc4b028fdd2b
(cherry picked from commit 4468d8728e07d9e74a8b08d8bf2d903cc4c5bbfc)