### 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
"""Base View to set Airflow related properties"""
    from airflow import macros
    route_base = ''
    extra_args = {
        
        'macros': macros,
        'get_docs_url': get_docs_url,
    }
    if not conf.getboolean('core', 'unit_test_mode'):
        extra_args['sqlite_warning'] = settings.Session.bind.dialect.name == 'sqlite'
        extra_args['sequential_executor_warning'] = conf.get('core', 'executor') == 'SequentialExecutor'
    line_chart_attr = {
        'legend.maxKeyLength': 200,
    }
    def render_template(self, *args, **kwargs):
        
        if TriggererJob.is_needed():
            kwargs["triggerer_job"] = lazy_object_proxy.Proxy(TriggererJob.most_recent_job)
        return super().render_template(
            *args,
            
            scheduler_job=lazy_object_proxy.Proxy(SchedulerJob.most_recent_job),
            **kwargs,
        )
def add_user_permissions_to_dag(sender, template, context, **extra):