Supplying this will prevent queue clashes between various ATAT sites
sharing the same Redis instance.
Note that the Celery documentation is currently wrong about the name for
configuring this:
https://docs.celeryproject.org/en/latest/userguide/configuration.html#std:setting-task_default_queue
It specifies `CELERY_TASK_DEFAULT_QUEUE`, but
`CELERY_DEFAULT_QUEUE` is the value that Celery currently looks for.
This appears to be fixed in on an upcoming release:
https://github.com/celery/celery/issues/5575
This is worth keeping an eye on, since the configuration key could
change in the future.
Adds a [kustomize](https://github.com/kubernetes-sigs/kustomize) overlay
for a new staging environment. Additionally, adds environment variables
in the place of certain pieces of information that need to be templated.
The K8s README ("deploy/README.md") has been updated to reflect the new
method for applying config.
This commit also removes the configuration for the AWS cluster and
references to AWS in the README.
