### Apache Airflow Provider(s)

google

### Versions of Apache Airflow Providers

apache-airflow-providers-google~=5.0

### Apache Airflow version

2.1.3 (latest released)

### Operating System

MacOS Big Sur

### Deployment

Astronomer

### Deployment details

_No response_

### What happened

The CloudSqlProxyRunner queries the Airflow DB directly to retrieve the GCP connection.

https://github.com/apache/airflow/blob/7b3a5f95cd19667a683e92e311f6c29d6a9a6a0b/airflow/providers/google/cloud/hooks/cloud_sql.py#L521

### What you expected to happen

In order to not break when using connections stored in external secrets backends, it should use standardized methods to retrieve connections and not query the Airflow DB directly.

### How to reproduce

Use a CloudSQLDatabaseHook with `use_proxy=True` while using an external secrets backend.

### Anything else

Every time

### 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/providers/google/cloud/hooks/cloud_sql.py
"""
        Stops running proxy.
        You should stop the proxy after you stop using it.
        """
        if not self.sql_proxy_process:
            raise AirflowException("The sql proxy is not started yet")
        else:
            self.log.info("Stopping the cloud_sql_proxy pid: %s", self.sql_proxy_process.pid)
            self.sql_proxy_process.kill()
            self.sql_proxy_process = None
        
        self.log.info("Removing the socket directory: %s", self.cloud_sql_proxy_socket_directory)
        shutil.rmtree(self.cloud_sql_proxy_socket_directory, ignore_errors=True)
        if self.sql_proxy_was_downloaded:
            self.log.info("Removing downloaded proxy: %s", self.sql_proxy_path)
            
            try:
                os.remove(self.sql_proxy_path)
            except OSError as e:
                if e.errno != errno.ENOENT:
                    raise
        else:
            self.log.info("Skipped removing proxy - it was not downloaded: %s", self.sql_proxy_path)
        if os.path.isfile(self.credentials_path):
            self.log.info("Removing generated credentials file %s", self.credentials_path)
            
            os.remove(self.credentials_path)
    def get_proxy_version(self) -> Optional[str]: