Changes

ttcn3-epdg: Set up params to get GTP-U echo working

Set the new module parameter added in the test.
Make sure the gtp_u_kmod osmo-epdg.config IP address is updated to the
proper docker network subnet.

Depends: osmo-ttcn3-hacks.git Change-Id I3fd96f212175959cb113d2f6a362c0e77e5ca0d7
Change-Id: I5cd9dcd6188227baed71823b0cbceb77dc771011

ttcn3-epdg: Test GTP-U userplane

Set the assigned IP address for the UE in the EPDG docker container on
the eth0 interface. This way the emulated UPF (ttcn3) can test
decaps+encaps of osmo-epdg tun by pinging the UE IP address and
expecting a pong back.

Related: OS#6235
Change-Id: Icc5710b42e5a5374aade6b952e1c543565ffad2e