Add button group css (#474)

Missed these when upgrading NHS frontend, which now has button groups
included.

Author: frankieroberto

app/views/_feedback-report.html

@@ -12,7 +12,7 @@ <h2 class="app-feedback-panel__title">You’ve just recorded your 5th vaccinatio
     <fieldset class="nhsuk-fieldset">
       <legend class="nhsuk-fieldset__legend nhsuk-u-margin-bottom-4">How was your experience of recording vaccinations?</legend>
 
-      <div class="app-button-group nhsuk-u-margin-bottom-0">
+      <div class="nhsuk-button-group nhsuk-u-margin-bottom-0">
 
         {{ button({
           text: "Very easy",
@@ -79,7 +79,7 @@ <h2 class="app-feedback-panel__title">Thank you.</h2>
     })}}
 
 
-    <div class="app-button-group nhsuk-u-margin-bottom-0">
+    <div class="nhsuk-button-group nhsuk-u-margin-bottom-0">
       {{ button({
         text: "Send feedback",
         classes: "nhsuk-button--secondary app-button--small"

app/views/regions/messages/show.html

@@ -27,7 +27,7 @@ <h1 class="nhsuk-leading-l">{{ pageName }}</h1>
       <p>Sent on {{ message.sentOn | govukDate }}.</p>
 
       <form action="/regions/messages/{{ message.id }}/decide" method="post">
-        <div class="app-button-group">
+        <div class="nhsuk-button-group">
           {{ button({
             text: "Approve",
             name: "decision",