fix: Add Omnibar Feature Flag (#12182)

* Update config.py

* Update config.py

superset/config.py

@@ -341,6 +341,8 @@ DEFAULT_FEATURE_FLAGS: Dict[str, bool] = {
     "ROW_LEVEL_SECURITY": False,
     # Enables Alerts and reports new implementation
     "ALERT_REPORTS": False,
+    # Enable experimental feature to search for other dashboards
+    "OMNIBAR": False,
 }
 
 # Set the default view to card/grid view if thumbnail support is enabled.