Describe the enhancement:
Update pod's metadata, and related hints-based configurations when node metadata or namespace metadata getting updated.

Describe a specific use case for the enhancement or feature:
(from a @jsoriano 's old comment):
An issue we have is that namespace metadata and hints are used when available when a pod is created or updated. But, if the namespace is modified, its metadata is not updated in pods events, and hints-based autodiscover is not retriggered. Pods need to be updated so the info from its namespaces is leveraged.
Perhaps we could have higher-level watchers and indexers that keep all the related metadata on sync, and this wouldn't be optional. E.g. the higher level pod watcher/informer would always internally have watchers/informers for pods, nodes and namespaces and would trigger updates with all the data if any of them change. The watcher used in add_kubernetes_metadata should do the same.