### Apache Airflow Provider(s)

snowflake

### Versions of Apache Airflow Providers

Versions 2.2.x (since https://github.com/apache/airflow/commit/0a37be3e3cf9289f63f1506bc31db409c2b46738).


### Apache Airflow version

2.2.1

### Operating System

Debian GNU/Linux 10 (buster)

### Deployment

Other 3rd-party Helm chart

### Deployment details

Bitnami Airflow Helm chart @ version 8.0.2

### What happened

When connecting to Snowflake via SQLAlchemy using the Snowflake Hook, I get an error that the URL is not valid because my Snowflake instance is in US West 2 (Oregon) which means I don't provide a region explicitly. Snowflake's documentation says:
> If the account is located in the AWS US West (Oregon) region, no additional segments are required and the URL would be xy12345.snowflakecomputing.com

The error is that `xy12345..snowflakecomputing.com` is not a valid URL (note the double-dot caused by the lack of a region).

### What you expected to happen

I expect the connection to be successful.

### How to reproduce

You can use the default snowflake connection if you have one defined and see this problem with the following one-liner:
```shell
python -c 'from airflow.providers.snowflake.hooks.snowflake import SnowflakeHook; SnowflakeHook().get_sqlalchemy_engine().connect()'
```

### Anything else

Fortunately I imagine the fix for this is just to leave the region URL component out when `region` is `None` here: https://github.com/apache/airflow/commit/0a37be3e3cf9289f63f1506bc31db409c2b46738#diff-2b674ac999a5b938fe5045f6475b0c5cc76e4cab89174ac448a9e1d41a5c04d5R215.

Using version `2.1.1` of the Snowflake provider with version `2.2.1` of Airflow is currently a viable workaround so for now I am just avoiding the update to the provider.

### 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/providers/snowflake/hooks/snowflake.py
"""Returns connection widgets to add to connection form"""
        from flask_appbuilder.fieldwidgets import BS3TextFieldWidget
        from flask_babel import lazy_gettext
        from wtforms import BooleanField, StringField
        return {
            "extra__snowflake__account": StringField(lazy_gettext('Account'), widget=BS3TextFieldWidget()),
            "extra__snowflake__warehouse": StringField(
                lazy_gettext('Warehouse'), widget=BS3TextFieldWidget()
            ),
            "extra__snowflake__database": StringField(lazy_gettext('Database'), widget=BS3TextFieldWidget()),
            "extra__snowflake__region": StringField(lazy_gettext('Region'), widget=BS3TextFieldWidget()),
            "extra__snowflake__role": StringField(lazy_gettext('Role'), widget=BS3TextFieldWidget()),
            "extra__snowflake__insecure_mode": BooleanField(
                label=lazy_gettext('Insecure mode'), description="Turns off OCSP certificate checks"
            ),
        }
    @staticmethod
    def get_ui_field_behaviour() -> Dict: