Migrate loading spinners to be design system compliant

What does this MR do and why?

Migrate loading spinners to be design system compliant. Related to 6 issues. I have verified all changes working as seen in screenshots/screencaptuers below.

1. #353753 (closed)
2. #353741 (closed)
3. #353740 (closed)
4. #353739 (closed)
5. #353738 (closed)
6. #353735 (closed)

Screenshots or screen recordings

_commit_box.html.haml

commit-box-html

_editor.html.haml

editor-html

_todo.html.haml

todo-haml

index.html.haml

todos-index

###_upload.html.haml

upload-html

edit.html.haml

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.