New HEALTHY_READONLY state should be operational state instead of health state?

In one of the other PRs, we are discussing to find which nodes are e healthy.

sodonnell pointed that, HEALTHY_READONLY should be operational state.

This Jira is to discuss, why it was added as health state and what is the background and possibility of correction.

https://github.com/apache/ozone/pull/3542#discussion_r909147369

CC: pifta erose nanda msingh @Jie Yao