SFTP Provider: Fix default folder permissions

[MatthieuBlais]

Relates #26226

Fixing default mode when creating a directory with paramiko and convert decimal mode to octal mode (paramiko documention)

• Updating test cases to confirm permissions after masking out the default umask are as we expect whenever we create a new folder.

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contribution Guide (https://github.com/apache/airflow/blob/main/CONTRIBUTING.rst)
Here are some useful points:

• Pay attention to the quality of your code (flake8, mypy and type annotations). Our pre-commits will help you with that.
• In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example DAG that shows how users should use it.
• Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
• Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
• Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
• Be sure to read the Airflow Coding style.
  Apache Airflow is a community-driven project and together we are making it better 🚀.
  In case of doubts contact the developers at:
  Mailing List: [email protected]
  Slack: https://s.apache.org/airflow-slack

[uranusjr]

I don’t think this is a good fix. Instead we should change the default to 0o777.

[MatthieuBlais]

@uranusjr I can change the default value to 511 which is 0o777 instead. My only concern is that this function mkdir in this class uses decimal value as well. I think it can be confusing if they don't follow the same approach. Is it better to update this function as well?

def mkdir(self, path: str, mode: int = 777) -> None:
        """
        Creates a directory on the remote system.
        :param path: full path to the remote directory to create
        :param mode: permissions to set the directory with
        """
        conn = self.get_conn()
        conn.mkdir(path, mode=int(str(mode), 8))

[uranusjr]

Change them both to use octal. Using decimal is a bug in the first place. (We can keep the str case to allow "755" so ease transition.) We can do this in a provider (and bump the major version).

[potiuk]

cool !