Resolve "Use one column form layout on Admin Area Settings page"

What does this MR do?

Updates Admin Area -> Settings page to use a single-column layout vs. the existing two-column layout.

In other words:

• change .form-group.row to .form-group
• convert labels using CSS classes col-form-label col-sm-2 to label-light
• remove any column offsetting
• fix issue with missing checked parameter with radio_button_tag
• fix HAML formatting

Screenshots

Before (two-column layout)

After (single-column layout)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes #44674 (closed)