Apply gl-form-input for search field in milestone page

app/views/shared/milestones/_search_form.html.haml

 = form_tag request.path, method: :get do |f|
   = search_field_tag :search_title, params[:search_title],
     placeholder: _('Filter by milestone name'),
-    class: 'form-control input-short',
+    class: 'form-control gl-form-input input-short',
     spellcheck: false
   = hidden_field_tag :state, params[:state]
   = hidden_field_tag :sort, params[:sort]

changelogs/unreleased/gl-form-milestone-search.yml

+---
+title: Apply gl-form-input for search field in milestone page
+merge_request: 58007
+author: Yogi (@yo)
+type: changed