Add ESS icons to Elasticsearch docs for supported Cloud settings

[lockewritesdocs]

The ES Docs do not indicate if a setting is supported on ESS. This discrepancy has resulted in support cases where a user tries an unsupported setting and it fails.

As part of the Cloud-first workgroup, the ES reference needs a PR like this one to add the ESS icon for supported settings, based on:

• Cloud docs (ESS whitelisted) - https://www.elastic.co/guide/en/cloud/current/ec-add-user-settings.html
• Code source of truth -https://github.com/elastic/cloud/tree/master/scala-services/adminconsole/src/main/resources/settings/elasticsearch

Output looks like https://www.elastic.co/guide/en/kibana/current/settings.html

It's possible that the Cloud docs are incomplete, meaning that settings are whitelisted but not documented anywhere. For example, these security settings are whitelisted in the Cloud docs, but are not shown as Cloud-compatible in the ES Audit Security Settings. Each of the supported settings should use the ESS icon.

Related to #48412.

[elasticmachine]

Pinging @elastic/es-search (:Search/Search)

[elasticmachine]

Pinging @elastic/es-docs (>docs)

[lockewritesdocs]

After discussion with the larger team, we decided to add the ESS icon for ES settings supported on Cloud, but not produce a full list. A separate PR will be opened by @gtback to develop an automated solution that reads through the ES configuration settings code and pulls tagged content for supported settings into a Cloud settings page.

This automated approach reduces maintenance overhead and ensures that we generate the full list of Cloud settings without having to manually build the page. When this automated solution is complete, we will build a complete list of Cloud settings, and also share the solution with the Kibana team so that they do the same.

cc: @nrichers for visibility