### 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
* **location** - The location of the Cloud SQL instance (for example europe-west1).
    * **database_type** - The type of the database instance (MySQL or Postgres).
    * **use_proxy** - (default False) Whether SQL proxy should be used to connect to Cloud
      SQL DB.
    * **use_ssl** - (default False) Whether SSL should be used to connect to Cloud SQL DB.
      You cannot use proxy and SSL together.
    * **sql_proxy_use_tcp** - (default False) If set to true, TCP is used to connect via
      proxy, otherwise UNIX sockets are used.
    * **sql_proxy_binary_path** - Optional path to Cloud SQL Proxy binary. If the binary
      is not specified or the binary is not present, it is automatically downloaded.
    * **sql_proxy_version** -  Specific version of the proxy to download (for example
      v1.13). If not specified, the latest version is downloaded.
    * **sslcert** - Path to client certificate to authenticate when SSL is used.
    * **sslkey** - Path to client private key to authenticate when SSL is used.
    * **sslrootcert** - Path to server's certificate to authenticate when SSL is used.
    :param gcp_cloudsql_conn_id: URL of the connection
    :type gcp_cloudsql_conn_id: str
    :param gcp_conn_id: The connection ID used to connect to Google Cloud for
        cloud-sql-proxy authentication.
    :type gcp_conn_id: str
    :param default_gcp_project_id: Default project id used if project_id not specified
           in the connection URL
    :type default_gcp_project_id: str
    """
    conn_name_attr = 'gcp_cloudsql_conn_id'
    default_conn_name = 'google_cloud_sqldb_default'
    conn_type = 'gcpcloudsqldb'
    hook_name = 'Google Cloud SQL Database'
    _conn = None  
    def __init__(