Use form_group attributes for search input

app/components/search_component.html.erb

@@ -1,17 +1,15 @@
 <%= form_with model: @user, url: path(current_user), method: "get", local: true do |f| %>
   <div class="app-search govuk-!-margin-bottom-4">
-    <div class="govuk-form-group app-search__form-group">
     <%= f.govuk_text_field :search,
+      form_group: {
+        class: "app-search__form-group",
+      },
       label: { text: search_label },
       type: "search",
       value:,
       autocomplete: "off",
       class: "app-search__input" %>
-    </div>
-
-    <button class="govuk-button app-search__button undefined" data-module="govuk-button">
-      Search
-    </button>
 
+    <%= f.govuk_submit "Search", classes: "app-search__button" %>
   </div>
 <% end %>