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.
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.
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.
