fix pg_vector extension requires SUPERUSER, but not available on Huawei Cloud RDS (#24093)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

api/core/rag/datasource/vdb/pgvector/pgvector.py

@@ -253,7 +253,8 @@ class PGVector(BaseVector):
                 return
 
             with self._get_cursor() as cur:
-                cur.execute("CREATE EXTENSION IF NOT EXISTS vector")
+                if dify_config.PGVECTOR_IS_OWNER:
+                    cur.execute("CREATE EXTENSION IF NOT EXISTS vector")
                 cur.execute(SQL_CREATE_TABLE.format(table_name=self.table_name, dimension=dimension))
                 # PG hnsw index only support 2000 dimension or less
                 # ref: https://github.com/pgvector/pgvector?tab=readme-ov-file#indexing