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
---
M jobs/osmo-gsm-tester-runner.yml
1 file changed, 18 insertions(+), 0 deletions(-)

diff --git a/jobs/osmo-gsm-tester-runner.yml b/jobs/osmo-gsm-tester-runner.yml
index db0a491..83040dc 100644
--- a/jobs/osmo-gsm-tester-runner.yml
+++ b/jobs/osmo-gsm-tester-runner.yml
@@ -257,6 +257,7 @@
               https://gerrit.osmocom.org/docker-playground \
               docker-playground
             git -C docker-playground log --oneline
+            make -C docker-playground/debian-buster-jenkins  # OS#6126
             make -C docker-playground/osmo-gsm-tester
 
             unlink osmo-gsm-tester/sysmocom/resources.conf || true

