Expose external Elasticsearch URL to Kibana plugins

[richkuz]

Describe the feature:

Please expose the external Elasticsearch URL value to Kibana plugins.

Describe a specific use case for the feature:

Enterprise Search provides an Elasticsearch API curl example usage in the UI.

Enterprise Search uses decodeCloudId to parse an Elasticsearch URL when running on Cloud. If there is no Cloud URL, Enterprise Search defaults to https://localhost:9200. More ideal would be an API to pull the external ES URL from config, but such a setting is not available to plugins today.

This feature also blocks this use case in the Elasticsearch dev console:
#77464

More context: #119862 (comment)

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[pgayvallet]

More ideal would be an API to pull the external ES URL from config

Following the discussions we had with the team during our previous grooming: If the external ES URL the one that Kibana uses to connect to ES, when in a Cloud environment? Or is Kibana accessing ES via an internal URL instead?

[TinaHeiligers]

We haven't heard any other requests for exposing the external ES Url to kibana plugins and I'm closing this issue as stale.
We can reopen if the need arises again.