Cleanup dead code

[matrss]

There are some code paths that are never used. One file that comes to mind, for which we have no coverage and that we decided against actually using: https://github.com/Open-MSS/MSS/blob/af7352611868f1e29421fde8ff5d84cbc295f029/mslib/msui/msui_web_browser.py

There is probably other code that is never used as well, e.g. some files have if __name__ == "__main__": blocks that AFAICT are not required.

We should search for those places and clean up a bit.

There are tools that can help in the search, one of them e.g. would be vulture: https://github.com/jendrikseipp/vulture. But there are also others.