GenericUI: don't add all inputs to automation vector

GenericUI: don't add all inputs to automation vector

That list is used to set the automation state of all automatable
controls when the global automation state is changed with the buttons at
the top of the generic UI window. The controls were added to the list
regardless of the automatable status, and some controls were even added
multiple times: once in build_control_ui() and once in build().

Since changing the state of non-automatable controls is wrong, only add
the control UI in build_control_ui() which already has the knowledge of
automatable or not.