Update workspace.mdx

Removed AI Assistant from Cube Cloud Workspace tools, since it is being deprecated.

Author: arynnmp

docs/pages/product/workspace.mdx

@@ -74,8 +74,7 @@ With Cube Core, you can:
 [ref-budgets]: /product/workspace/budgets
 [ref-prefs]: /product/workspace/preferences
 [ref-cli]: /product/workspace/cli
-[ref-ai-assistant]: /product/workspace/ai-assistant
 [ref-semantic-catalog]: /product/workspace/semantic-catalog
 [ref-encryption-keys]: /product/workspace/encryption-keys
 [ref-cube-store-encryption]: /product/caching/running-in-production#data-at-rest-encryption
-[ref-visual-model]: /product/workspace/visual-model
+[ref-visual-model]: /product/workspace/visual-model