Resolve "Check usage of /app/views/projects/update.js.haml"

What does this MR do?

Related to #250837 (closed)

Part of the initiative to remove inline javascript.

This MR removes javascript that was supposed to process the form with AJAX and save a reload, but during my initial discovery, I noticed the form reloads the page anyway.

I decided to just delete the file and update the controller and forms accordingly since:

1. The forms are already "broken" by reloading
2. This is the smallest possible change to accomplish the goal of removing inline javascript

Screenshots (strongly suggested)

There are no visual changes, but this the section that is affected. All of the forms on this page except for transferring and deleting a repo.

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides

Availability and Testing

To test:

1. Open any repo
2. Navigate to Settings / General
3. Change anything on any form and save
4. Forms should save as expected and display a success flash at the top of the screen