[Security Solution][Detection Rules]Update schema to match app Mitre ATT&CK validation

[dplumlee]

With the update of the app's Mitre ATT&CK validation in #85481, the detection engine schema wasn't updated with the expectation there would be more overhauled changes to the Mitre fields coming in 7.12. Those have since been reprioritized to a later release so we need to update the Mitre schema, specifically the technique field, to be optional and update the corresponding and affected pre-built rules to match.

[MadameSheema]

@dplumlee is there any work missing? Thanks :)

[dplumlee]

@MadameSheema we updated the schema to fit this ticket, but the rules themselves won't be updated from the detections side of things until after 7.13 per this ticket. We can probably close this ticket though, the work on our side is done

[peluja1012]

PR for this work is here #92281. Closing.

[ghost]

Hi @MadameSheema

We have validated this ticket on 7.12.0 BC2 and found that issue is Fixed. We observed that threat techniques is optional. User can add the tactic without threat techniques

Build Details:

Version: 7.12.0 BC2
Build: 39000
Commit: 4f65a5a1268fa78f1af9117d12312e1cee433376
Artifacts: https://staging.elastic.co/7.12.0-37f40745/summary-7.12.0.html

Screenshots:

Please let us know if any other scenarios need to be tested.

Thanks!!

[ghost]

Bug Conversion:

Created 01 Test-Case for this Ticket
https://elastic.testrail.io/index.php?/cases/view/76929

Thanks!!