Apply new GitLab UI style to mirror update button

changelogs/unreleased/yo-gl-button-mirror-update.yml

+---
+title: Apply new GitLab UI style to mirror update button and add space after icon
+merge_request: 51808
+author: Yogi (@yo)
+type: other

ee/app/views/shared/_mirror_update_button.html.haml

 - if @project.mirror? && can?(current_user, :push_code, @project)
   .gl-mb-3
     - if @project.import_state.mirror_update_due?
-      %span.btn.disabled
-        = sprite_icon('retry', css_class: 'spin')
+      %span.btn.gl-button.disabled
+        = sprite_icon('retry', css_class: 'spin gl-mr-3')
         = ('Update Scheduled…')
     - elsif @project.import_state.updating_mirror?
-      %span.btn.disabled
-        = sprite_icon('retry', css_class: 'spin')
+      %span.btn.gl-button.disabled
+        = sprite_icon('retry', css_class: 'spin gl-mr-3')
         = ('Updating…')
     - elsif can?(current_user, :admin_project, @project)
       = link_to update_now_project_mirror_path(@project), method: :post, class: 'btn' do
-        = sprite_icon('retry')
+        = sprite_icon('retry', css_class: 'gl-mr-3')
         = ('Update Now')
     - else
-      %span.btn.disabled
-        = sprite_icon('retry')
+      %span.btn.gl-button.disabled
+        = sprite_icon('retry', css_class: 'gl-mr-3')
         = ('Update Now')
     - if @project.mirror_last_update_succeeded?
       %p.inline.gl-ml-3