Change variable drawer edit action button

What does this MR do and why?

Updates the edit variable action to Save changes instead of Edit variable

Why?

• It's sort of confusing seeing Edit as the confirm button when you've finished filling out the form (reported in Slack)

Screenshots or screen recordings

Before	After

How to set up and validate locally

Project > settings > ci/cd > variables

Links

✂️ UX Paper Cuts 16.8 → Accessibility (#424396 - closed)