Update third party login styles

What does this MR do and why?

This MR is meant to solve: #372787 (closed) It solves an Issue with alignment of the 3rd party providers of the redesigned sign-in page.

Screenshots or screen recordings

before	after

How to set up and validate locally

This is unfortunately a little bit of a pain to reproduce, since I couldn't find a way to configure multiple 3rd party providers on a GDK.

I worked with the following hack, which should be good enough for demo purposes

1. enable restyle_login_page
2. go to login page
3. execute the script below

let container = document.querySelector('.omniauth-container');
let form = container.querySelector('form');
let numberOfClones = 6;
for (let i = 0; i < numberOfClones; i++) {
  let clone = form.cloneNode(true);
  form.parentElement.appendChild(clone);
}

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