### 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
match = re.search(r"_copy(\d+)$", selected_conn.conn_id)
            if match:
                conn_id_prefix = selected_conn.conn_id[: match.start()]
                new_conn_id = f"{conn_id_prefix}_copy{int(match.group(1)) + 1}"
            else:
                new_conn_id += '_copy1'
            dup_conn = Connection(
                new_conn_id,
                selected_conn.conn_type,
                selected_conn.description,
                selected_conn.host,
                selected_conn.login,
                selected_conn.password,
                selected_conn.schema,
                selected_conn.port,
                selected_conn.extra,
            )
            try:
                session.add(dup_conn)
                session.commit()
                flash(f"Connection {new_conn_id} added successfully.", "success")
            except IntegrityError:
                flash(
                    f"Connection {new_conn_id} can't be added. Integrity error, probably unique constraint.",
                    "warning",
                )
                session.rollback()
        self.update_redirect()
        return redirect(self.get_redirect())
    def process_form(self, form, is_created):