snabbnfv: bump telnet timeout for selftest
snabbnfv: bump telnet timeout for selftest

When run in a docker container for CI, the telnet timeout
was more likely to trigger and would block the test from
running. This commit approximately doubles the timeout.

eugeneia/snabb,Igalia/snabb,snabbco/snabb,SnabbCo/snabbswitch,alexandergall/snabbswitch,snabbco/snabb,alexandergall/snabbswitch,snabbco/snabb,Igalia/snabb,eugeneia/snabb,eugeneia/snabb,eugeneia/snabb,snabbco/snabb,Igalia/snabbswitch,alexandergall/snabbswitch,alexandergall/snabbswitch,Igalia/snabbswitch,Igalia/snabbswitch,alexandergall/snabbswitch,snabbco/snabb,Igalia/snabb,Igalia/snabbswitch,eugeneia/snabb,Igalia/snabbswitch,Igalia/snabb,eugeneia/snabb,alexandergall/snabbswitch,Igalia/snabb,snabbco/snabb,eugeneia/snabb,SnabbCo/snabbswitch,alexandergall/snabbswitch,Igalia/snabb,snabbco/snabb,Igalia/snabb,Igalia/snabb,eugeneia/snabb,SnabbCo/snabbswitch,SnabbCo/snabbswitch,alexandergall/snabbswitch,snabbco/snabb