Use groove for volume dialog slider

Previously we had a track line that stopped below the max val, creating
the illusion that at ~90%, volume level is full. It looked misaligned
next to a 100% slider.

Bug: b/289814874
Test: Manual. Groove height should match progress button at 100%.
Change-Id: Ifd2d7acdac7b6a154728536b096ac0dbd1d40b3d