**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
tests/serialization/test_dag_serialization.py
return self.__dict__ == other.__dict__
        def __ne__(self, other):
            return not self.__eq__(other)
    @parameterized.expand(
        [
            (None, None),
            ([], []),
            ({}, {}),
            ("{{ task.task_id }}", "{{ task.task_id }}"),
            (["{{ task.task_id }}", "{{ task.task_id }}"]),
            ({"foo": "{{ task.task_id }}"}, {"foo": "{{ task.task_id }}"}),
            ({"foo": {"bar": "{{ task.task_id }}"}}, {"foo": {"bar": "{{ task.task_id }}"}}),
            (
                [{"foo1": {"bar": "{{ task.task_id }}"}}, {"foo2": {"bar": "{{ task.task_id }}"}}],
                [{"foo1": {"bar": "{{ task.task_id }}"}}, {"foo2": {"bar": "{{ task.task_id }}"}}],
            ),
            (
                {"foo": {"bar": {"{{ task.task_id }}": ["sar"]}}},
                {"foo": {"bar": {"{{ task.task_id }}": ["sar"]}}},
            ),
            (
                ClassWithCustomAttributes(
                    att1="{{ task.task_id }}", att2="{{ task.task_id }}", template_fields=["att1"]
                ),
                "ClassWithCustomAttributes("
                "{'att1': '{{ task.task_id }}', 'att2': '{{ task.task_id }}', 'template_fields': ['att1']})",
            ),
            (
                ClassWithCustomAttributes(