ci/ci-tron: deduplicate setting the runner tags for most jobs

etnaviv is the important exception, as it needs to set two fields for
the setup tags, which need to be handled individually as runner tags.

The other exception is the nightly vangogh job that has a custom tag
added, which I'll hopefully get rid of Soon™.

One farm's jobs were also missing farm:$RUNNER_FARM_LOCATION; this
change ensures that it's always set, avoiding the risk of accidentally
picking an equivalent device in another farm.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34795>

.gitlab-ci/test/gitlab-ci.yml

@@ -437,6 +437,9 @@ yaml-toml-shell-py-test:
     - job: python-artifacts
       artifacts: true
     - !reference [.required-for-hardware-jobs, needs]
+  tags:
+    - farm:$RUNNER_FARM_LOCATION
+    - $B2C_MARS_SETUP_TAGS
 
   before_script:
     # We don't want the tarball unpacking of .test, but will take the JWT bits.