Simplify rxconfig template (#1492)

reflex/.templates/jinja/app/rxconfig.py.jinja2

@@ -5,6 +5,4 @@ class {{ config_name }}(rx.Config):
 
 config = {{ config_name }}(
     app_name="{{ app_name }}",
-    db_url="{{ const.db_url }}",
-    env=rx.Env.DEV,
 )