jobs/osmo-gsm-tester-runner: build debian-buster-jenkins

Fix the failing osmo-gsm-tester_virtual job by building the docker image
it depends on first, debian-buster-jenkins.

We are migrating most of the CI infrastructure away from old debian
versions to debian 12, but this is not possible here as explained in
OS#6126.

Related: OS#6126
Change-Id: I5f7468a402d82e3b6ee03b4f792ae7e3aae3942b
1 file changed