wacom-stylus-page: Tweak CcListRows from the "Grip Pen" section

• Use CcListRow:secondary-label instead of adding a GtkLabel as a suffix widget
• Use CcListRow:show-arrow instead of adding a GtkImage as a suffix widget
• Remove CcListRow:activatable=True properties
  as CcListRows are activatable by default
• Remove the underlines from the CcListRow:secondary-label values as mnemonics don't work in this case. This won't regress a11y because the mnemonics are already present in the CcListRow titles

Before	After