Remove clusters_integrations_elastic_stack metric from UsagePing

What does this MR do and why?

Remove clusters_integrations_elastic_stack metric from UsagePing.

Updates specs for usage_data.

Screenshots or screen recordings

NA

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #360195 (closed)