qt: Remove an obscure option no-one cares about

Remove the "Display addresses" setting checkbox. It doesn't do what
the tooltip says, and seems kind of pointless in any case.

Fixes #4580.

Conflicts:
	src/qt/forms/optionsdialog.ui
	src/qt/optionsdialog.cpp
	src/qt/optionsmodel.cpp
	src/qt/optionsmodel.h