### 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
"""Pre update hook."""
        item.execution_date = timezone.make_aware(item.execution_date)
        item.value = XCom.serialize_value(item.value)
def lazy_add_provider_discovered_options_to_connection_form():
    """Adds provider-discovered connection parameters as late as possible"""
    def _get_connection_types() -> List[Tuple[str, str]]:
        """Returns connection types available."""
        _connection_types = [
            ('fs', 'File (path)'),
            ('mesos_framework-id', 'Mesos Framework ID'),
            ('email', 'Email'),
        ]
        providers_manager = ProvidersManager()
        for connection_type, provider_info in providers_manager.hooks.items():
            if provider_info:
                _connection_types.append((connection_type, provider_info.hook_name))
        return _connection_types
    ConnectionForm.conn_type = SelectField(
        lazy_gettext('Connection Type'),
        choices=sorted(_get_connection_types(), key=itemgetter(1)),
        widget=Select2Widget(),
        validators=[InputRequired()],
        description="""
            Connection Type missing?
            Make sure you've installed the corresponding Airflow Provider Package.
        """,
    )
    for key, value in ProvidersManager().connection_form_widgets.items():
        setattr(ConnectionForm, key, value.field)
class ConnectionFormWidget(FormWidget):