jobs: master: also trigger once per day

Recently we had changes to osmo-ci, and I noticed that although some master
builds were broken by that, the builds were still showing success -- of twenty
days ago.

Run each master build at least once a day to indicate odd side effect failure
sooner.

Change-Id: I126de2bab3db22cb693b0fa665f6579de9238fdf

jobs/master-builds.yml

@@ -300,6 +300,7 @@
       - pollscm:
           cron: "H/5 * * * *"
           ignore-post-commit-hooks: false
+      - timed: "H H * * *"
 
     builders:
       - shell: '{obj:cmd}'