**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
count += 1
                dag = current_app.dag_bag.get_dag(dr.dag_id)
                tis_to_clear = dag_to_tis.setdefault(dag, [])
                tis_to_clear += dr.get_task_instances()
            for dag, tis in dag_to_tis.items():
                cleared_ti_count += len(tis)
                models.clear_task_instances(tis, session, dag=dag)
            flash(f"{count} dag runs and {cleared_ti_count} task instances were cleared")
        except Exception:
            flash('Failed to clear state', 'error')
        return redirect(self.get_default_url())
class LogModelView(AirflowModelView):
    """View to show records from Log table"""
    route_base = '/log'
    datamodel = AirflowModelView.CustomSQLAInterface(Log)  
    class_permission_name = permissions.RESOURCE_AUDIT_LOG
    method_permission_name = {
        'list': 'read',
    }
    base_permissions = [
        permissions.ACTION_CAN_READ,
        permissions.ACTION_CAN_ACCESS_MENU,
    ]
    list_columns = ['id', 'dttm', 'dag_id', 'task_id', 'event', 'execution_date', 'owner', 'extra']
    search_columns = ['dag_id', 'task_id', 'event', 'execution_date', 'owner', 'extra']
    base_order = ('dttm', 'desc')
    base_filters = [['dag_id', DagFilter, lambda: []]]
    formatters_columns = {
        'dttm': wwwutils.datetime_f('dttm'),
        'execution_date': wwwutils.datetime_f('execution_date'),