[BUG] Screenshot needs to be updated for the new UI for AI Assistant

[muskangulati-qasource]

Documentation links

https://www.elastic.co/docs/solutions/security/ai/ai-assistant-knowledge-base#_option_1_enable_knowledge_base_from_an_ai_assistant_conversation

Description

Actual Screenshot

Expected Screenshot

Which documentation set(s) does this bug apply to?

ESS and serverless

Release version

This bug applies to Elastic Stack 9.1.0 and above releases

Testing environment

Build deployed from the production cloud environment: https://cloud.elastic.co/

[muskangulati-qasource]

@arvindersingh-qasource please review!

[arvindersingh-qasource]

Reviewed and Assigned to @natasha-moore-elastic

[natasha-moore-elastic]

Related to #1932.