[FEATURE] Remove the internal security-enabled requirement for batch HA

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [x] I have searched in the [issues](https://github.com/apache/kyuubi/issues?q=is%3Aissue) and found no similar issues.

### Describe the feature

Configure REST API high availability mode without setting `kyuubi.engine.security.enabled` to `true`

### Motivation

Currently `kyuubi.engine.security.enabled` must be set to `true` and use ZooKeeper znode to store the secret to enable REST API high availavility mode, but we can technically relax the requirement as we now have a mechanism to configure pre-shared secret without ZooKeeper dependency.

### Describe the solution

_No response_

### Additional context

This idea comes from https://github.com/apache/kyuubi/pull/7418#issuecomment-4350391087

### Are you willing to submit PR?

- [ ] Yes. I would be willing to submit a PR with guidance from the Kyuubi community to improve.
- [x] No. I cannot submit a PR at this time.

Start by reading the REST API high availability configuration and the handling of kyuubi.engine.security.enabled. Compare the ZooKeeper znode secret path with the pre-shared secret mechanism, and review the discussion in PR 7418. Done means REST API high availability can be configured without enabling the internal security requirement, with coverage for the supported configuration paths.

Written by the indexing model from the issue text.