**Apache Airflow version**: 2.1.0

**Browsers**: Chrome and Firefox

**What happened**:

Before upgrading to 2.1.0

![before](https://user-images.githubusercontent.com/14293802/120359517-c1ca1100-c2d5-11eb-95ba-58ccc0a3ac37.png)

After upgrading to 2.1.0

![after](https://user-images.githubusercontent.com/14293802/120359528-c4c50180-c2d5-11eb-8e04-f34846ea2736.png)

**What you expected to happen**:

Show/Edit/Delete under Security -> Users are available

<!-- What do you think went wrong? -->

**How to reproduce it**:

Go to Security -> Users (as an admin of course) 
airflow/www/views.py
return super().render_template(
            *args,
            
            scheduler_job=lazy_object_proxy.Proxy(SchedulerJob.most_recent_job),
            **kwargs,
        )
def add_user_permissions_to_dag(sender, template, context, **extra):
    """
    Adds `.can_edit`, `.can_trigger`, and `.can_delete` properties
    to DAG based on current user's permissions.
    Located in `views.py` rather than the DAG model to keep
    permissions logic out of the Airflow core.
    """
    if 'dag' in context:
        dag = context['dag']
        can_create_dag_run = current_app.appbuilder.sm.has_access(
            permissions.ACTION_CAN_CREATE, permissions.RESOURCE_DAG_RUN
        )
        dag.can_edit = current_app.appbuilder.sm.can_edit_dag(dag.dag_id)
        dag.can_trigger = dag.can_edit and can_create_dag_run
        dag.can_delete = current_app.appbuilder.sm.has_access(
            permissions.ACTION_CAN_DELETE,
            permissions.RESOURCE_DAG,
        )
        context['dag'] = dag
before_render_template.connect(add_user_permissions_to_dag)
class Airflow(AirflowBaseView):
    """Main Airflow application."""
    @expose('/health')
    def health(self):