add tolerations/nodeselector to migration job template (fixes #1774)

[ranvit]

SUMMARY

As described in #1774, the migration pod has no provisions to add tolerations to it. This PR's solution is to use the postgres pod's toleration/selector on the migration job.

The docs would need to be updated to alert the user about this relationship between postgres and the migration pod

ISSUE TYPE

• Bug, Docs Fix or other nominal change

[rooftopcellist]

@ranvit Is there a reason why postgres_tolerations and postgres_node_selector is used instead of task_tolerations and task_node_selector?

My thinking here is that specifying postgres_ params might not make sense in some scenarios, for example external db scenarios.

The k8s db migration job uses the task container, and previously this was running in the task container, so using task_* params for this might be a bit more intuitive.

Also, could you add some docs here to make this a bit more discoverable for users?

• https://github.com/ansible/awx-operator/blob/devel/docs/user-guide/advanced-configuration/assigning-awx-pods-to-specific-nodes.md

[ranvit]

@rooftopcellist thank you for the feedback. It makes sense for this migration job to utilize the task_* settings.

I decided to implement this the same way the Task pods have been configured here so that we get the benefit of falling back to the global node assignment settings

Also updated the docs!

[rooftopcellist]

I tested this out on my cluster and it works as expected as far as I can tell. No errors on fresh install either.

@ranvit Thanks for the PR!

[ranvit]

@rooftopcellist how do you feel about adding the same tolerations/nodeSelector fallback on the Backup role's db-management pod?

I could go through every k8s pod template in the repo and add the same fix