Validate namespace scale out

[markstory]

During our production rollout, we'll need to build out multiple taskbroker clusters, which implies multiple kafka topics, broker deployments and worker pool deployments.

• Improve our k8s resource definitions so that we can deploy multiple broker + worker pools
• Improve our k8s resource definitions so that we can deploy workers that consume a subset of namespaces. Having single namespace worker pools will be useful as we start rolling out taskworkers in production.