tasks: Fix OpenShift instances

[martinpitt]

Commit 93523ff broke OpenShift deployments: The export HOME from setup-tasks isn't visible in the main cockpit-tasks loop, so the GitHub API fails to resolve the user's home dir.

Put it back for now. This is far from elegant, but we need to unbreak the statistics queue quickly.

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http://webhook-cockpit.apps.ocp.cloud.ci.centos.org/inspect-queue is building up a lot of pending statistics requests, it fails with

Traceback (most recent call last):
File "/work/bots/./run-queue", line 36, in <module>
from task import distributed_queue
File "/work/bots/task/__init__.py", line 51, in <module>
api = github.GitHub()
^^^^^^^^^^^^^^^
File "/work/bots/task/github.py", line 157, in __init__
self.log = Logger(self.cache.directory)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/work/bots/task/github.py", line 71, in __init__
os.makedirs(directory, exist_ok=True)
File "<frozen os>", line 215, in makedirs
File "<frozen os>", line 225, in makedirs
PermissionError: [Errno 13] Permission denied: '/.cache'

[martinpitt]

Crap, it still fails, no idea now.

[martinpitt]

OK, fixed, deployed, and it's catching up with the statistics queue now.