### Apache Airflow version

main (development)

### Operating System

macOS 11.5.2

### Versions of Apache Airflow Providers

_No response_

### Deployment

Virtualenv installation

### Deployment details

_No response_

### What happened

If your first try fails and you have retries enabled, the subsequent tries skip right to the final `next_method(**next_kwargs)` instead of starting with `execute` again.

### What you expected to happen

Like we reset things like start date, we should wipe `next_method` and `next_kwargs` so we can retry the task from the beginning.

### How to reproduce

_No response_

### Anything else

_No response_

### 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/taskinstance.py
if conf.has_option('email', key):
                    path = conf.get('email', key)
                    with open(path) as f:
                        content = f.read()
                return jinja_env.from_string(content).render(**jinja_context)
            subject = render('subject_template', default_subject)
            html_content = render('html_content_template', default_html_content)
            html_content_err = render('html_content_template', default_html_content_err)
        return subject, html_content, html_content_err
    def email_alert(self, exception):