**Description**
In the trigger page, there is a text area to enter (optional) conf json. It would be great if a sample JSON can be provided programatically while defining DAG

**Use case / motivation**

This will improve usability of the UI that triggers a DAG

tests/www/test_views.py
"""Do not show external links if log handler is local."""
        url = f'{endpoint}?dag_id=example_bash_operator'
        with self.capture_templates() as templates:
            self.client.get(url, follow_redirects=True)
            ctx = templates[0].local_context
            self.assertFalse(ctx['show_external_log_redirect'])
            self.assertIsNone(ctx['external_log_name'])
    @parameterized.expand(["graph", "tree"])
    @mock.patch('airflow.utils.log.log_reader.TaskLogReader.log_handler', new_callable=PropertyMock)
    def test_show_external_log_redirect_link_with_external_log_handler(self, endpoint, mock_log_handler):
        """Show external links if log handler is external."""
        class ExternalHandler(ExternalLoggingMixin):
            LOG_NAME = 'ExternalLog'
            @property
            def log_name(self):
                return self.LOG_NAME
        mock_log_handler.return_value = ExternalHandler()
        url = f'{endpoint}?dag_id=example_bash_operator'
        with self.capture_templates() as templates:
            self.client.get(url, follow_redirects=True)
            ctx = templates[0].local_context
            self.assertTrue(ctx['show_external_log_redirect'])
            self.assertEqual(ctx['external_log_name'], ExternalHandler.LOG_NAME)
class TestConfigurationView(TestBase):
    def test_configuration_do_not_expose_config(self):