Use positive condition for legacy flag check

Changed from 'if not legacy' to 'if legacy' for better readability.
The positive condition directly maps to the flag name and avoids mental negation.

Author: sfc-gh-svishnu

src/snowflake/cli/_plugins/streamlit/streamlit_entity.py

@@ -107,10 +107,10 @@ def deploy(
                 f"Streamlit {self.model.fqn.sql_identifier} already exists. Use 'replace' option to overwrite."
             )
 
-        if not legacy:
-            self._deploy_versioned(bundle_map=bundle_map, replace=replace, prune=prune)
-        else:
+        if legacy:
             self._deploy_legacy(bundle_map=bundle_map, replace=replace, prune=prune)
+        else:
+            self._deploy_versioned(bundle_map=bundle_map, replace=replace, prune=prune)
 
         return self.perform(EntityActions.GET_URL, action_context, *args, **kwargs)