### Apache Airflow version

2.1.3 (latest released)

### Operating System

Debian Buster

### Versions of Apache Airflow Providers

_No response_

### Deployment

Managed Services (Astronomer, Composer, MWAA etc.)

### Deployment details

Running `quay.io/astronomer/ap-airflow:2.1.3-buster` Docker image

### What happened

In the task attributes view of a BashOperator, the `template_ext` row doesn't show any value, while I would expect to see `('.sh', '.bash')`.

![image](https://user-images.githubusercontent.com/6249654/131467817-8620f68d-0f3d-491d-ad38-cbf5b91cdcb3.png)


### What you expected to happen

Expect to see correct `template_ext` value

### How to reproduce

Run a BashOperator and browse to Instance Details --> scroll down to `template_ext` row

### Anything else

Spent a little time trying to figure out what could be the reason, but haven't found the problem yet. Therefore created issue to track.

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

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]: