Airflow 2.1.0, Docker

**What happened**:

Users with the Guest role assigned are stuck in a redirect loop once they attempt to login successfully to the web interface.

**What you expected to happen**:

Get minimal access to the dashboard with the appropriate views for a guest role

**How to reproduce it**:
1. Assign a guest role to any user and remove any other roles with the administrator user.
2. Logout from the admin account 
3. Login as the guest user
4. You will notice constant HTTP redirects, and the dashboard will not show up.


tests/www/test_security.py
with self.app.app_context():
            user = mock.MagicMock()
            user.is_anonymous = True
            self.app.config['AUTH_ROLE_PUBLIC'] = 'Admin'
            
            user.roles = self.app.appbuilder.sm.get_user_roles(user)
            assert user.roles == [self.app.appbuilder.sm.get_public_role()]
            test_dag_ids = ["test_dag_id_1", "test_dag_id_2", "test_dag_id_3"]
            for dag_id in test_dag_ids:
                self._create_dag(dag_id)
            self.security_manager.sync_roles()
            for dag_id in test_dag_ids:
                assert self.app.appbuilder.sm.can_read_dag(dag_id, user) is True
                assert self.app.appbuilder.sm.can_edit_dag(dag_id, user) is True
                assert self._has_dag_perm(permissions.ACTION_CAN_READ, dag_id, user) is True
                assert self._has_dag_perm(permissions.ACTION_CAN_EDIT, dag_id, user) is True
    def test_get_user_roles(self):
        user = mock.MagicMock()
        user.is_anonymous = False
        roles = self.appbuilder.sm.find_role('Admin')
        user.roles = roles
        assert self.security_manager.get_user_roles(user) == roles
    def test_get_user_roles_for_anonymous_user(self):