Changes

jobs/build-kernels-testenv: new jobs

Prepare to replace the docker-playground based jobs for running
osmo-ggsn in QEMU with a kernel built from source with testenv.

Split the part that builds the kernels into extra jobs that export the
built kernels as artifacts. This makes it easier to use kernels outside
of jenkins too and it allows retriggering only a testsuite run without
also building the kernel again.

The fragment.config is imported from docker-playground current master
978adc, path: ttcn3-ggsn-test/osmo-ggsn-kernel/fragment.config

Change-Id: Id64a1a778fa38eec20498c36b390332f75d7d3f5

jobs: gerrit-verifications.yml: Add job for upf-benchmark.git

Change-Id: I7212e8f88c731993af01e0e42ddaad6dd7291c37

jobs/build-kernels-testenv: notify-every-unstable-build: true

Fix that this wasn't set to true (copy paste error).

Change-Id: Icf2127e34caa40675fd8e24bc3e061325eb6c0b0

jobs/build-kernels-testenv: add build-kernel-none

Create a dummy output/linux file, that the jobs generated by
ttcn3-testsuites-testenv can copy (via copyartifact) when setting the
kernel to "none".

Without this, the ttcn3-testsuites-testenv.yml would need to become more
complex, as it is not possible in jenkins job builder templates to only
do the copyartifact block conditionally if kernel != "none".

Another solution would be using shell logic like the following:

  if [ "$KERNEL" != "none" ]; then
    wget -q -O .linux "https://jenkins.osmocom.org/..."
  fi

But this has the disadvantage that jenkins is not aware of the file and
therefore we cannot track easily which linux kernel build was used in
the job. With the copyartifact method, we can click on "See
Fingerprints" and find which job built the kernel. Example:
https://jenkins.osmocom.org/jenkins/job/ttcn3-ggsn-test-kernel-net-next/147/fingerprints/

Change-Id: I0b2367558a2b73c06267bc65f17cfcc224f35002