**Apache Airflow version**:
v2.0.0

**What happened**:

Custom operators inheriting from DummyOperator are go in to a scheduled state, where as DummyOperator itself is set straight to success.

**What you expected to happen**:

All operators should be successfully executed.

**How to reproduce it**:

```py
from datetime import datetime
from airflow import DAG
from airflow.operators.dummy_operator import DummyOperator

class MyJob(DummyOperator):
    template_fields_renderers = {
        "body": "json"
    }
    template_fields = ("body",)

    def __init__(self, body, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.body = body

with DAG(
    dag_id="test",
    schedule_interval=None,
    start_date=datetime(2020, 8, 13),
) as dag:
    MyJob(task_id="aaaa", body={"aaa": "bbb"})

```

**Anything else we need to know**:
This is a known problem that we will fix, see: https://github.com/apache/airflow/pull/10956#discussion_r502492775
airflow/models/baseoperator.py
:param resources: A map of resource parameter names (the argument names of the
        Resources constructor) to their values.
    :type resources: dict
    :param run_as_user: unix username to impersonate while running the task
    :type run_as_user: str
    :param task_concurrency: When set, a task will be able to limit the concurrent
        runs across execution_dates
    :type task_concurrency: int
    :param executor_config: Additional task-level configuration parameters that are
        interpreted by a specific executor. Parameters are namespaced by the name of
        executor.
        **Example**: to run this task in a specific docker container through
        the KubernetesExecutor ::
            MyOperator(...,
                executor_config={
                    "KubernetesExecutor":
                        {"image": "myCustomDockerImage"}
                }
            )
    :type executor_config: dict
    :param do_xcom_push: if True, an XCom is pushed containing the Operator's
        result
    :type do_xcom_push: bool
    """
    
    template_fields: Iterable[str] = ()
    
    template_ext: Iterable[str] = ()
    
    template_fields_renderers: Dict[str, str] = {}