Fix MyPy errors for Airflow decorators

[josh-fell]

Related: #19891

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[github-actions]

The PR most likely needs to run full matrix of tests because it modifies parts of the core of Airflow. However, committers might decide to merge it quickly and take the risk. If they don't merge it quickly - please rebase it to the latest main at your convenience, or amend the last commit of the PR, and push it with --force-with-lease.

[josh-fell]

@uranusjr @potiuk I pushed some other changes here to fix decorators more generally. I'm still not quite sure how to resolve this error though:

airflow/decorators/__init__.py:45: error: Cannot assign to a type
            _TaskDecorator = _DockerTask

A cast() resolves the issue but I'm not sure if this is the proper fix given the code context.

[ashb]

@uranusjr @potiuk I pushed some other changes here to fix decorators more generally. I'm still not quite sure how to resolve this error though:

airflow/decorators/__init__.py:45: error: Cannot assign to a type
            _TaskDecorator = _DockerTask

A cast() resolves the issue but I'm not sure if this is the proper fix given the code context.

This is us playing tricks for IDE support. A # type: ignore or a cast() is perfectly valid solution to that.