Remove Deprecated "Collect Logs from third-party REST API" for 9.0

[qcorporation]

Parent Issue:
https://github.com/elastic/dev/issues/2802

Issue:
Based upon the work done from the parent issue, for the 9.0 release, Integrations would like to remove deprecated options entirely.
Collect logs from third-party REST API
For:

• Zeek
• Nginx
• Windows
• Apache
• System
• AWS CloudTrail

[elasticmachine]

Pinging @elastic/sec-deployment-and-devices (Team:Security-Deployment and Devices)

[andrewkroh]

The release of these changes should coincide with the timing of the 9.0 Elastic stack release. We should prepare the changes before then so that they are ready, but we hold off on the merge until 9.0 ships.

[muthu-mps]

@qcorporation - There is one more integration which is not included in this issue is AWS cloudtrail that's currently using the deprecated input. Is this integration already tracked somewhere?

• Also noticed that this feature is still in experimental for this integration.

  Collect CloudTrail logs from third-party REST API (experimental)

[qcorporation]

@qcorporation - There is one more integration which is not included in this issue is AWS cloudtrail that's currently using the deprecated input. Is this integration already tracked somewhere?

• Also noticed that this feature is still in experimental for this integration.
  Collect CloudTrail logs from third-party REST API (experimental)

@muthu-mps I didn't know about this. We had originally marked the targeted integrations with a (deprecation) warning before we actually pulled the trigger on removing it. I'm glad to do it, I just need to make sure that product is aligned with that decision.

@jamiehynds @norrietaylor are you OK to remove CloudTrail as well - it's marked as experimental but there's no forewarning of deprecation. Would it be OK to remove it with the other integrations?