Fixed content description for clock face width slider

This CL aims at fixing the content description for clock face width
slider. This ensures that we announce the range as well as the label
when focussed on the clock face width slider.

Bug: b/418223312
Flag: EXEMPT bugfix
Test: Tested by building & installing picker on local, and checking if
the content description contains range and label as well.

Change-Id: I42fd17a4e26b29688af5225fb373d64830d73530