[chronik] Don't erase the default websocket timeout un chronik_ws_script

Summary: The timeout is set at client creation time and adapts itself to the situation, with an extended value for the slow machines. Overriding the default timeout where it is not useful only increases the risk of timeout.

Test Plan:

./test/functional/test_runner.py chronik_ws_script

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14799