**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
logging.config.dictConfig(DEFAULT_LOGGING_CONFIG)
        self.clear_table(TaskInstance)
        
        
        for mod in [m for m in sys.modules if m not in self.old_modules]:
            del sys.modules[mod]
        sys.path.remove(self.settings_folder)
        shutil.rmtree(self.settings_folder)
        self.logout()
        super().tearDown()
    @parameterized.expand(
        [
            [State.NONE, 0, 0],
            [State.UP_FOR_RETRY, 2, 2],
            [State.UP_FOR_RESCHEDULE, 0, 1],
            [State.UP_FOR_RESCHEDULE, 1, 2],
            [State.RUNNING, 1, 1],
            [State.SUCCESS, 1, 1],
            [State.FAILED, 3, 3],
        ]
    )
    def test_get_file_task_log(self, state, try_number, expected_num_logs_visible):