hide echoing to serial port in testapi calls from output in screenshots
As a user using videos recorded by openQA I don't want to get confused by weird hash strings seen in screenshots and videos so that these videos can also be used as simple instruction videos and are easier to understand by everyone.
- AC1: No auto-generated content is shown in terminals that is not explicitly coming from the tests
- AC2: The existing behaviour of
declare -r PROMPT_COMMAND="fc -nl -1 2>&1 > $serialdev"
when setting the bash-prompt, e.g. where we set it to '$ ' or '# ', to forward the output of the last command to the serial port. To do what we did before using
hashed_string we can try to rely on internal tools of the SUT for this. It's linux specific at this point anyway so it might even be a good idea to move it completely out of the (lower-level) of the testapi at all.