[Internal]: Fix heading levels on Circuit breaker settings

### Description

The heading hierarchy on [Circuit breaker settings](https://www.elastic.co/docs/reference/elasticsearch/configuration-reference/circuit-breaker-settings) is inconsistent. Most breaker sections are H3 under the page H1, then EQL, ES|QL, and Synonym jump to H2. Machine learning is H3, so it nests under ES|QL in the table of contents even though it is a separate breaker.

This already ships on the published page. [elastic/elasticsearch#156600](https://github.com/elastic/elasticsearch/pull/156600) continues the same pattern for the new native memory section.

### Resources

- Published page: https://www.elastic.co/docs/reference/elasticsearch/configuration-reference/circuit-breaker-settings
- Source: [`docs/reference/elasticsearch/configuration-reference/circuit-breaker-settings.md`](https://github.com/elastic/elasticsearch/blob/main/docs/reference/elasticsearch/configuration-reference/circuit-breaker-settings.md) in `elastic/elasticsearch`
- Related PR: https://github.com/elastic/elasticsearch/pull/156600

### Which deployment methods does this change impact?

Elastic On-Prem and Cloud (all)

### What Elastic Stack release is this request related to?

N/A

### Collaboration model

The documentation team will create the first draft

### Point of contact.

**Main contact:** @shainaraskas

Start with docs/reference/elasticsearch/configuration-reference/circuit-breaker-settings.md and compare its heading hierarchy with the published page. Check the EQL, ES|QL, Synonym, and machine learning sections, then verify that each breaker appears at the intended level in the table of contents and that the documentation checks pass.

Written by the indexing model from the issue text.