[DOCS] Add deprecated monitoring settings

[lcawl]

Summary

This PR adds monitoring settings that were mentioned in #29496 to the Kibana User Guide. Related to #29979

NOTE: https://www.elastic.co/guide/en/kibana/master/monitoring-settings-kb.html currently says "There are also xpack.monitoring.elasticsearch.* settings, which support the same values as Kibana configuration settings", so it might not be required to repeat each of these.

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

- [ ] This was checked for cross-browser compatibility, including a check against IE11
- [ ] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support

• Documentation was added for features that require explanation or tutorials
  - [ ] Unit or functional tests were updated or added to match the most common scenarios
  - [ ] This was checked for keyboard-only and screenreader accessibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately
• This includes a feature addition or change that requires a release note and was labeled appropriately

[skip ci]

[elasticmachine]

Pinging @elastic/stack-monitoring

[lcawl]

These settings will not be duplicated here after all.