Remove any all.scss files in favour of index.scss

[romaricpascal]

What

Remove any all.scss file from our repository, as our codebase has been updated to use index.scss files instead. The removed files will have been deprecated by #4955 and #4988 so should be safe to remove, but worth double checking.

Why

This will complete the replacement of all.scss files started by #4955 and #4988, whose benefits are listed in #4955.

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

• All all.scss files have been removed from the repository