Fix kubernetes executor watcher kube_client_request_args shadowing

[insomnes]

Fix KubernetesJobWatcher shadowing kube client timeouts arguments

Provided change allows to have previously established defaults in KubernetesJobWatcher for client timeouts to not hang on events reading, but also do not overwrite them if they were provided in specific configuration option by user.

closes: #45517

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[boring-cyborg]

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[insomnes]

I've checked failed tests in previous checks run
https://github.com/apache/airflow/actions/runs/12698225501

And I can't find any reason for my changes to interfere with them. So I've rebased branch again

[RNHTTR]

No need to set the placeholder vars

[insomnes]

Added as suggested. I am not familiar with code standards, so I was trying to minimize my "invasion".

Thank you!