Remove polluted .ui.right (#26825)

Each change is tested manually line by line. There are too many changes
so I can't share dozens of screenshots.

In short:

1. `ui right` could be still used in `ui top attached header`, because
there is a special case.
2. A lot of `ui right` are just no-op, so they can be removed safely.
3. Some of the `ui right` should be replaced by `gt-float-right` (to
avoid breaking, leave them to the future).
4. A few of the `ui right` could be rewritten by flex.

templates/user/settings/repos.tmpl

@@ -32,7 +32,7 @@
 									{{else}}
 										<span class="icon gt-dib gt-pt-3">{{svg "octicon-file-directory-fill"}}</span>
 										<span class="name gt-dib gt-pt-3">{{$.ContextUser.Name}}/{{$dir}}</span>
-										<div class="ui right">
+										<div class="gt-float-right">
 											{{if $.allowAdopt}}
 												<button class="ui button green show-modal gt-p-3" data-modal="#adopt-unadopted-modal-{{$dirI}}"><span class="icon">{{svg "octicon-plus"}}</span><span class="label">{{$.locale.Tr "repo.adopt_preexisting_label"}}</span></button>
 												<div class="ui g-modal-confirm modal" id="adopt-unadopted-modal-{{$dirI}}">