Allow hints based autodiscover based on namespace metadata

[exekias]

Once we get namespace metadata in #13873, it should be possible to use it for hints based autodiscover.

Users should be able to set hints at the namespace level, so they don't need to repeat them across all pods in the namespace. Hints from the namespace and the Pod should be merged. If one is present in both the namespace and the pod, the one in the Pod overrides the namespace's.

For instance, adding this hint to a namespace should make Filebeat ignore logs from all its pods: co.elastic.logs/enabled: false. While if co.elastic.logs/enabled: true is added to a pod in the namespace, its logs should be retrieved.

[exekias]

cc @odacremolbap @ChrsMark @sorantis

[jsoriano]

This could be a fix for some use cases related to #9123

[botelastic]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[sorantis]

keep open

[jsoriano]

Would this be solved by #16321?

[ChrsMark]

Would this be solved by #16321?

Looks like yes! @exekias could you confirm that?

[exekias]

++ closing