[AIRFLOW-4136] fix key_file of hook is overwritten by SSHHook connection (#5558)
[AIRFLOW-4136] fix key_file of hook is overwritten by SSHHook connection (#5558)

Prevent overwrite of key_file by connection if parameter was provided to SSHHook

(cherry picked from commit d3884493c74a49bea7fc8f825c531baa3f948bec)

owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow