Fix Web-IDE Error message

What does this MR do?

References #36852 (closed)

The Error message on the WebIDE looked kind of broken with odd spacing on top and the button having an hard to read colour. This is now fixed by removing the white text and the spacing.

Update Replaced the inner of the component with GitLab UI component to be in line wit our general look. Had to replace it on the inside of the error_message component due to otherwise complex refactor of bigger parts of the WebIDE.

I also completely updated the specs to be in line with our latest approaches, run faster (no need for localVue) and the spec cases now cover more ground following the users interactions.

Screenshots

Before:

With GlAlert Component: