Decrease upgrade job resource requests

Quay upgrade job has the following resource requests/limits as of 3.6.0:

resources:
  requests:
    cpu: 2000m
    memory: 8Gi
  limits:
    cpu: 2000m
    memory: 8Gi

There may be some room for improvement, specially when it comes to resource requests. The migration runs Python's alembic, on this scenario the bulk of work would be deferred to the postgres instance and not the pod running the migration.

 Acceptance criteria

• Requests are shrunk to its minimum requirements
• A test case exists to validate the new values (database should contain data)