ENYO-641: Slider: Turning Off and On Percentage erases Negative Values

Issue.

The sampler has an inconsistent showcase of the percentage label. The first slider is set to show a percentage, while the preceding sliders show values (RGB and Negatives).

Fix.

Disable Show Percentages on the first Slider, and Uncheck the Show Percentages option, so that all sliders transition labels to values or percentages at the same time.

Enyo-DCO-1.1-Signed-off-by: Derek Anderson <derek.anderson@lge.com>