In some buttons (specifically, the "Manage printers" button), the tooltip arrow is being drawn even though the tooltip text is empty. This commit fixes that by making sure that the background rectangle (PointingRectangle) of the tooltip is not be visible if the height of the tooltip is 0.
CURA-8334
This was a bit of a weird setup, so i removed it. This way the tooltip can be used
in the same way as the regular tooltip (by simply setting the visibility)
CURA-6004