### Apache Airflow version

2.2.0

### Operating System

Debian buster

### Versions of Apache Airflow Providers

_No response_

### Deployment

Astronomer

### Deployment details

astro dev start

### What happened

When I have tried to duplicate a connection first time it has created a connection with hello_copy1 and duplicating the same connection second time giving me an error of 
```Connection hello_copy2 can't be added. Integrity error, probably unique constraint.```




### What you expected to happen

It should create a connection with name hello_copy3 or the error message should be more user friendly.

### How to reproduce

https://github.com/apache/airflow/pull/15574#issuecomment-912438705

### Anything else

Suggested Error 
```
Connection hello_copy2 can't be added because it already exists.
```
or
Change the number logic in _copyN so the new name will be always unique.


### Are you willing to submit PR?

- [ ] 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/www/views.py
"""Returns appropriate permission name depending on request method name."""
        if request:
            action_name = request.view_args.get("name")
            _, method_name = request.url_rule.endpoint.rsplit(".", 1)
            if method_name == 'action' and action_name:
                return self.class_permission_name_mapping.get(action_name, self._class_permission_name)
            if method_name:
                return self.class_permission_name_mapping.get(method_name, self._class_permission_name)
        return self._class_permission_name
    @class_permission_name.setter
    def class_permission_name(self, name):
        self._class_permission_name = name
class CustomUserLDAPModelView(MultiResourceUserMixin, UserLDAPModelView):
    """Customize permission names for FAB's builtin UserLDAPModelView."""
    pass
class CustomUserOAuthModelView(MultiResourceUserMixin, UserOAuthModelView):
    """Customize permission names for FAB's builtin UserOAuthModelView."""
    pass
class CustomUserOIDModelView(MultiResourceUserMixin, UserOIDModelView):
    """Customize permission names for FAB's builtin UserOIDModelView."""
    pass
class CustomUserRemoteUserModelView(MultiResourceUserMixin, UserRemoteUserModelView):
    """Customize permission names for FAB's builtin UserRemoteUserModelView."""
    pass