Changes

ttcn3-bts-test: add --no-warnings to bpftrace

Since switching to debian 13 and having bpftrace 0.23.2 instead of
0.17.0, bpftrace is constantly printing warnings. Turn off warnings by
default so we don't end up filling up the disk space of jenkins runners
while ttcn3-bts-test runs for >2h.

We can turn on warnings in copies of the main jenkins job for
development, while also ensuring that we only run a few tests instead of
the whole testsuite.

Warnings look like this:

  root@deb12build-ansible:/home/osmocom-build/jenkins/workspace/ttcn3-bts-test/logs/bts/bpftrace# head udp_sendmsg_delay.log
  [Thu Jan 15 01:31:13 UTC 2026] respawn: 0: starting: /data/bpftrace/udp_sendmsg_delay.sh
  + pidof osmo-bts-trx
  + bpftrace /data/bpftrace/udp_sendmsg_delay.bt -p 9
  Attaching 3 probes...
  Tracing udp_sendmsg() latency... Hit Ctrl-C to end.
  /data/bpftrace/udp_sendmsg_delay.bt:29:3-13: WARNING: Invalid argument
  Additional Info - helper: get_ns_current_pid_tgid, retcode: -22
    @start[tid] = nsecs;
    ~~~~~~~~~~
  /data/bpftrace/udp_sendmsg_delay.bt:30:3-13: WARNING: Invalid argument

Change-Id: I0e4c62f27f67d4b8601516ce5c1ebfa415331b4a