Base text-only face's minimum size on the preferred size of legend

Otherwise we only show two sets of "..." due to eliding both the label and value of the sensors.

Before	After

BUG: 434189 FIXED-IN: 5.22

Depends on frameworks/kquickcharts!30 (merged)

Also contains two other commits, one to limit the height of the legend when it's being constrained, the other to slightly increase the maximum width so we don't go into two-column mode as quickly.