Changes

ttcn3-ggsn-ogs: Rename config files

Let's make names similar to what's used in PGW_Tests. Also, in
open5gs.git, config files don't contain the "d" at the end.

Change-Id: If56d1a890a4f1b80b4f04ae22644f9cb9cdd35f4

ttcn3-pgw-test: Log stdout to find crashes

Change-Id: I573637866787ce1f613bd56a009251578c98cbf3

ttcn3-pgw-test: Use process name in log file

This way it becomes similar to what we use in ttcn3-ggsn-tests-ogs.

Change-Id: Ibac0e6bc9dc7c2e576a4f5d1ccb730211d1e1427

ttcn3-{pgw,ggsn}-tests: Add comment with procedure to get open5gs-smfd bt automatically

Some specific gdb commands need to be run in open5gs-smfd to get the
desired result (some signals need to be ignored).
gdb use is not enabled by default. Furthermore, if one wants to use it,
editing the Dockerfile to install gdb is required.

Change-Id: I1ac8b77e84d57040fc09964356bc8a01e5d721e3

ttcn3-pgw-tests: use same bootstrap for upfd as in ttcn-ggsn-tests-ogs

This approach has several benefits:
* We end up with ip/tun setup output in the same log file as
  open5gs-upfd process output.
* We configure all ip/tun *before* the open5gs-upfd process starts.

Furthermore, we have same procedure as in ttcn3-ggsn-tests-ogs, which
simplifies maintainment/use.

The IP address pool for UEs is still different in pgw-tests and
ggsn-tests-ogs. We can make them the same in subsequent patches.

Change-Id: I94219abbeb5e004ce707407b5aa5ee8ad6c3a80e

ttcn3-pgw-test: Log open5gs-nrfd stdout/stderr

This way we see potential crashes.

Change-Id: I31f2ff2dd5daa68756e910c4cb91acefdad50cb1

ttcn3-{ggsn,pgw}-test: Avoid open5gs itself logging to a file

We already log stdout/stderr to a file, so there's no need to log a file
internally. We prefer logging that through stdout/stderr in order to
catch more stuff, like segfaults.

Change-Id: Ifdc010f26abdc8cefeec0c72a1f617911ec375d7