Adds the "Enable threat intelligence integrations" page

[nastasha-solomon]

• Adds content to the Solutions and use cases > Security > Get Started > Ingest data to Elastic Security > Enable threat intelligence integrations page
• Removes raw migrated files (ESS and Serverless) for the "Enable threat intelligence integrations" page
• Renamed an image that contained "serverless" in it (changed serverless--getting-started-threat-intelligence-view.png to getting-started-threat-intelligence-view.png) and one other ref to the file

Preview:

• Enable threat intelligence integrations