[AIRFLOW-6040] ReadTimeoutError should not raise exception

[dimberman]

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Issue link: AIRFLOW-6040

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[dimberman]

continuation of #6643

[dimberman]

cc: @pvcnt @sbrandtb

[sbrandtb]

@dimberman I do not fully agree with making this a warning. Warnings often confuse people and this read timeout is totally expected. I would even demote it to debug because we would only look into this if something is fishy anyways.

[maxirus]

I don't think this is the right approach for fixing AIRFLOW-6040. The Watcher isn't being ran in its own thread so it must timeout so it's not blocking further execution. Therefor it's not an error or a warning as this is the expected behavior you're looking for.

[sbrandtb]

@maxirus While I agree with this being the wrong approach to fix the issue, I beg to differ: Yes, it is not run in a separate thread. But it is run in a separate process.