[Security GenAI] "Select a Connector" popup does not show up after th…

…e user selects any connector and then cancels it from Endpoint Insights. (elastic#208907) (elastic#208969)

## Summary

BUG: elastic#208907

This PR fixes the issue where user cannot select a different connector
type after mistakenly selecting a wrong one.

### Steps to reproduce without required endpoint installation:

1. Make sure there are no connectors
2. Open "AI Assistant" on one of the security solution pages
3. Press "(+) Add connector" button
4. Connector type selection modal is visible
5. Select "Amazon Bedrock" type (or any other connector type)
6. Cancel the modal
7. Press "(+) Add connector" button again

**ISSUE**: previously selected connector type is being displayed and
there is no way to switch between types
**EXPECTED**: we should show connector type selection modal once
previous one was closed

### Issue recording

https://github.com/user-attachments/assets/48052bf1-4e00-43b7-a63e-f8a7969b9dbf

### Fixed state recording

https://github.com/user-attachments/assets/48be1cc4-0326-43a1-bd57-bb82fc1f19eb
(cherry picked from commit b28036a)

x-pack/packages/kbn-elastic-assistant/impl/connectorland/connector_selector/index.tsx

@@ -217,7 +217,7 @@ export const ConnectorSelector: React.FC<Props> = React.memo(
             <AddConnectorModal
               actionTypeRegistry={actionTypeRegistry}
               actionTypes={actionTypes}
-              onClose={() => setIsConnectorModalVisible(false)}
+              onClose={cleanupAndCloseModal}
               onSaveConnector={onSaveConnector}
               onSelectActionType={(actionType: ActionType) => setSelectedActionType(actionType)}
               selectedActionType={selectedActionType}