CI: do not waste cycles building for BeagleBone Black

Yup, we use that for the calibration device, but hey, we aren't
periodically updating our SW in there, so let's save about 20 minutes of
CI time by skipping this job.

Change-Id: I86d5ae798b8e40a89df5c7b795d35ad5e905029c
diff --git a/.zuul.yaml b/.zuul.yaml
index a127ae3..bd3854f 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -48,7 +48,7 @@
             post-run: ci/post.yaml
             roles:
               - zuul: return-built-artifact
-        - czechlight-beagleboneblack
+        # - czechlight-beagleboneblack
 
     promote:
       jobs: