Switch LoggingMixin to return structlog.BoundLogger

[dstandish]

Body

This is so that we can switch to structlog universally in the airflow codebase, which lets us use its features re binding vars and context vars.

I started work on this in #46897 but have to drop it for now. Anyone with time and interest could pick it up. May just need to fix the tests.

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[jx2lee]

@dstandish Could i take this? I'll work on this. and small question, why does it be changed structlog? Any ref link to be helpful 🥹 (also, Please assign to me)