[Security Solution] [Bug] On switching Knowledge Base Index Sharing from `Private` to `Global` shows `Error updating Knowledge Base Entries`

[arvindersingh-qasource]

Describe the bug On switching Knowledge Base Index Sharing from Private to Global shows Error updating Knowledge Base Entries

Kibana/Elasticsearch Stack version

VERSION: 8.16.0 BC3
BUILD: 79556
COMMIT: f02d1303b5230c357ac7e4c49c8adadd5f66af38

Pre Conditions

1. Kibana v8.16.0 build be must be available
2. AI Connector must be configured.
3. Custom Knowledge Base Index with Sharing as Private should be created.
4. Below mentioned xpack must be enabled in Kibana

   xpack.securitySolution.enableExperimental:
   - 'assistantKnowledgeBaseByDefault'

Steps

1. Navigate to Management -> AI Assistant - Knowledge Base
2. For pre requisite Custom Knowledge Base Index with Sharing as Private , click on ✏ icon to edit Index.
3. Switch Sharing from Private to Global.
4. Click on Save button.
5. Observe that there will be an error as Error updating Knowledge Base Entries

Expected Result User should be able to switch Knowledge Base Index Sharing from Private to Global without any error.

Screen recording

https://github.com/user-attachments/assets/2078fe9b-b86c-4801-bbf7-96cb20635759

[elasticmachine]

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

[arvindersingh-qasource]

@muskangulati-qasource Please review this ticket.

Thanks.

[muskangulati-qasource]

Reviewed and assigned to @MadameSheema