### 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
raise AirflowException(f"The sql proxy is already running: {self.sql_proxy_process}")
        else:
            command_to_run = [self.sql_proxy_path]
            command_to_run.extend(self.command_line_parameters)
            self.log.info("Creating directory %s", self.cloud_sql_proxy_socket_directory)
            Path(self.cloud_sql_proxy_socket_directory).mkdir(parents=True, exist_ok=True)
            command_to_run.extend(self._get_credential_parameters())
            self.log.info("Running the command: `%s`", " ".join(command_to_run))
            self.sql_proxy_process = Popen(command_to_run, stdin=PIPE, stdout=PIPE, stderr=PIPE)
            self.log.info("The pid of cloud_sql_proxy: %s", self.sql_proxy_process.pid)
            while True:
                line = (
                    self.sql_proxy_process.stderr.readline().decode('utf-8')
                    if self.sql_proxy_process.stderr
                    else ""
                )
                return_code = self.sql_proxy_process.poll()
                if line == '' and return_code is not None:
                    self.sql_proxy_process = None
                    raise AirflowException(
                        f"The cloud_sql_proxy finished early with return code {return_code}!"
                    )
                if line != '':
                    self.log.info(line)
                if "googleapi: Error" in line or "invalid instance name:" in line:
                    self.stop_proxy()
                    raise AirflowException(f"Error when starting the cloud_sql_proxy {line}!")
                if "Ready for new connections" in line:
                    return
    def stop_proxy(self) -> None: