server tests : more pythonic process management; fix bare `except:` (#6146)

* server tests : remove seemingly redundant newlines in print()

* server tests : use built-in subprocess features, not os.kill and psutil

* server tests : do not catch e.g. SystemExit; use print_exc

* server tests: handle TimeoutExpired exception

* server tests: fix connect on dual-stack systems

* server: tests: add new tokens regex on windows generated following new repeat penalties default changed in (#6127)

* server: tests: remove the hack on windows since now we get the good socket family

* server: tests: add new tokens regex following new repeat penalties default changed in (#6127)

* server: tests: add new tokens regex following new repeat penalties default changed in (#6127)

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Co-authored-by: Pierrick HYMBERT <pierrick.hymbert@gmail.com>