mgw: add module param mp_enable_conn_timeout_test

Fix ttcn3-mgw-latest by not running "conn-timeout 0" during f_init_vty
at the start of every test case. The latest osmo-mgw release does not
have that command yet.

Change-Id: I8bbf15baa45679d5812a5a9184520ef9b9e73bba
1 file changed