Changes

ttcn3-ggsn-test-ogs: run smf in 4g only mode

Remove the SBI related configuration, so open5gs-smf does not attempt to
connect to the NRF every few seconds.

Fix for:
  [sbi] WARNING: [299d78ae-fae5-41ee-84a3-dbd9fa117ce7] Retry registration with NRF (../lib/sbi/nf-sm.c:182)
  [sbi] WARNING: [7] Failed to connect to 127.0.1.10 port 7777 after 200 ms: Couldn't connect to server (../lib/sbi/client.c:698)

Change-Id: I61d60e6e71b671c3deb20cc7ff8abb81ea4d5f03