[Accessibility] Color Contrast address UX bugs

Reformatted xml files and added constraints to make sure texts do not go
out of bound.

Test: local raven device
Screenshot: attached on bug
Bug: 329176991, 329169251
Flag: aconfig
com.android.settings.accessibility.enable_color_contrast_control

Change-Id: I7cb15a46557f54833c77fe41928fb6e98d5ec519