Add `HSTS` header to `healthz` endpoint response

[rishabh-11]

How to categorize this issue?

/area robustness
/kind enhancement
/priority 4

What would you like to be added:
Add HSTS header to the HTTP response from the health endpoint of mcm. Refer etcd-backup-restore for an example.

Why is this needed:
The HSTS header is absent from the HTTP response from the health endpoint, making it vulnerable to man-in-the-middle attacks.