Include volume type in volume metricset data from Kubernetes module

[eedugon]

Describe the enhancement:

Currently our Metricbeat Kubernetes volume is not collecting volume types in the volume metricset.

Kubernetes volumes can be of many different types, and many of them might be unwanted by the users in certain visualizations or even during data collection. Examples of volume types are: Secret, ConfigMap, HostPath, EmptyDir, PersistentVolumeClaim.

It would be very useful to include the volume type into the field kubernetes.volume.type, which is currently not offered.

In case of supporting this, ideally we should also offer in the metricset the capacity of filtering out incoming data, in the same way as we do in the system-->filesystem metricset with filesystem.ignore_types. We could offer this with something like volume.ignore_types.

I also believe implementing this should be easy as the type is part of the volume metadata.

The same should be applied to Elastic Agent Kubernetes integration.

Describe a specific use case for the enhancement or feature:

Kubernetes monitoring and wanting to optimize data collection.

[elasticmachine]

Pinging @elastic/obs-ds-hosted-services (Team:obs-ds-hosted-services)