tasks: Reinstate $HOME for OpenShift task runner

Commit 6ac8ab6 dropped setting `$HOME` from the cockpit-tasks main
loop script. But the task runner still needs it to write to the GitHub
cache. It previously tried to write into `/.cache`, which got an EPERM.

As a bonus, this now also sets a correct $HOME with `oc rsh` or the web
UI terminal.

Author: martinpitt

tasks/cockpit-tasks-centosci.yaml

@@ -18,6 +18,9 @@ spec:
       - name: cockpit-tasks
         image: quay.io/cockpit/tasks
         env:
+        # containers run as random user ID without passwd entry
+        - name: HOME
+          value: /work
         - name: RUN_STATISTICS_QUEUE
           value: '1'
         - name: COCKPIT_GITHUB_TOKEN_FILE