PP-2904: Vizier heartbeat should send more information about cluster state to Pixie cloud.

Summary: We will now send K8s version, (max 10) unhealthy data plane pod statuses, and also include pod/container restart counts in the PodStatus in the Vizier heartbeat. This information will be picked up by cloud and written to the db for debugging purposes.

Test Plan: edited existing proto_utils, ran Vizier.

Reviewers: michelle, vihang, zasgar

Reviewed By: zasgar

JIRA Issues: PP-2904

Differential Revision: https://phab.corp.pixielabs.ai/D9455

GitOrigin-RevId: 73720d3cf2b25649a35861d27206a3d76a4b7c5e

Author: Natalie Serrino