### 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/serialization/serialized_objects.py
"""
        Deserialize Operator Links if the Classes  are registered in Airflow Plugins.
        Error is raised if the OperatorLink is not found in Plugins too.
        :param encoded_op_links: Serialized Operator Link
        :return: De-Serialized Operator Link
        """
        from airflow import plugins_manager
        plugins_manager.initialize_extra_operators_links_plugins()
        if plugins_manager.registered_operator_link_classes is None:
            raise AirflowException("Can't load plugins")
        op_predefined_extra_links = {}
        for _operator_links_source in encoded_op_links:
            
            
            #
            
            #
            
            
            
            
            
            
            #