Follow-up: merge/squash /api/healthz and /healthz endpoints

[mjudeikis-bot]

Summary

After PR #505 merges, we will have two health endpoints:

• /healthz
• /api/healthz

This issue tracks the follow-up work to:

1. Test both endpoints after Add httpz into server always for k/k to work #505 lands
2. Investigate if they can be squashed into a single endpoint
3. Remove duplication if safe to do so

Related: #505