**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
upstream = True
        else:
            upstream = False
        if not self._dag:
            return self.priority_weight
        from airflow.models.dag import DAG
        dag: DAG = self._dag
        return self.priority_weight + sum(
            map(
                lambda task_id: dag.task_dict[task_id].priority_weight,
                self.get_flat_relative_ids(upstream=upstream),
            )
        )
    @cached_property
    def operator_extra_link_dict(self) -> Dict[str, Any]:
        """Returns dictionary of all extra links for the operator"""
        op_extra_links_from_plugin: Dict[str, Any] = {}
        from airflow import plugins_manager
        plugins_manager.initialize_extra_operators_links_plugins()
        if plugins_manager.operator_extra_links is None:
            raise AirflowException("Can't load operators")
        for ope in plugins_manager.operator_extra_links:
            if ope.operators and self.__class__ in ope.operators:
                op_extra_links_from_plugin.update({ope.name: ope})
        operator_extra_links_all = {link.name: link for link in self.operator_extra_links}
        
        operator_extra_links_all.update(op_extra_links_from_plugin)
        return operator_extra_links_all
    @cached_property
    def global_operator_extra_link_dict(self) -> Dict[str, Any]: