Prevent .form-actions from leaking out of the container (originally by @pavelloz)

addition This MR was originally by @pavelloz in !4889 (closed), the MR was inactive for 2 months and is a P3, I have credited @pavelloz in the CHANGELOG. The description below is also copied from that MR.

What does this MR do?

Fixes div width leaking outside

Are there points in the code the reviewer needs to double check?

Any place where it might been needed when introduced couple months ago.

Why was this MR needed?

What are the relevant issue numbers?

addition Closes #18731 (closed).

Screenshots (if relevant)

Before

After

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

cc @jschatz1