**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
"""Redirect to home if TI does not exist or if log handler is local"""
        url_template = "redirect_to_external_log?dag_id={}&task_id={}&execution_date={}&try_number={}"
        try_number = 1
        url = url_template.format(self.DAG_ID, task_id, quote_plus(self.DEFAULT_DATE.isoformat()), try_number)
        response = self.client.get(url)
        self.assertEqual(302, response.status_code)
        self.assertEqual('http://localhost/home', response.headers['Location'])
    @mock.patch('airflow.utils.log.log_reader.TaskLogReader.log_handler', new_callable=PropertyMock)
    def test_redirect_to_external_log_with_external_log_handler(self, mock_log_handler):
        class ExternalHandler(ExternalLoggingMixin):
            EXTERNAL_URL = 'http://external-service.com'
            def get_external_log_url(self, *args, **kwargs):
                return self.EXTERNAL_URL
        mock_log_handler.return_value = ExternalHandler()
        url_template = "redirect_to_external_log?dag_id={}&task_id={}&execution_date={}&try_number={}"
        try_number = 1
        url = url_template.format(
            self.DAG_ID, self.TASK_ID, quote_plus(self.DEFAULT_DATE.isoformat()), try_number
        )
        response = self.client.get(url)
        self.assertEqual(302, response.status_code)
        self.assertEqual(ExternalHandler.EXTERNAL_URL, response.headers['Location'])
class ViewWithDateTimeAndNumRunsAndDagRunsFormTester: