CORE-17312
Hide everything under the same foreground & background colors, so that
the actual color and text blanking reset does not create a visual "blinking".
Then, blank the text and finally reset the actual foreground &
background colors.
We do this because we cannot do the screen scrolling trick that would
allow to change both the text and the colors at the same time (the
function is currently not available in our console "emulation" layer).