Use single column layout for user settings

What does this MR do and why?

• Use single layout for profile settings
• Use gl-text-secondary for section subtitles

What does this MR not do?

• Content changes (help text, etc)
• Expand/collapse sections

Screenshots or screen recordings

Before	After

How to set up and validate locally

Go to user > preferences > profile

UX Paper Cuts 16.2 → Settings UI (#398215 - closed)