[Security Solution] [Bug] The default Elastic AI Assistant is not available on 8.18.0

[muskangulati-qasource]

Describe the bug
The default Elastic AI Assistant is not available on 8.18.0

Kibana/Elasticsearch Stack version

VERSION: 8.18.0
BUILD: 82206
COMMIT: 33e6754d67870b0e403266b752c3973539506cc6

Steps

1. Kibana version 8.18.0 or above should exist
2. There should be no AI connector added
3. Navigate to the Attack Discovery tab under Security
4. Click on the 'Ask AI Assistant' button
5. Observe that Elastic AI Assistant is not available for testing

Expected Result
The default Elastic AI Assistant should be available on 8.18.0 as per feature ticket: https://github.com/elastic/security-team/issues/11369

Screenshot

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)

[muskangulati-qasource]

@amolnater-qasource please review!

[amolnater-qasource]

Reviewed & assigned to @MadameSheema