Bug 1844742 Deleting wallpost confirm screen yes button missing styles

Fix puts in the correct classes for the button styles to be displayed.

behatnotneeded

Change-Id: I2197e73a69be96d805f4196692496778173a8564

htdocs/blocktype/wall/deletepost.php

@@ -43,6 +43,7 @@ $form = pieform(array(
         ),
         'submit' => array(
             'type'  => 'submitcancel',
+            'class' => 'btn-secondary button',
             'value' => array(get_string('yes'), get_string('no')),
             'goto'  => $goto,
         ),

htdocs/theme/raw/plugintype/blocktype/wall/templates/inlineposts.tpl

 <div id="wall" class="wall">
     {if $wallmessage}
-        <div class="lead text-small text-center">{$wallmessage}</div>
+        <div class="card-body lead text-small text-center">{$wallmessage}</div>
     {/if}
     {if $wallposts}
         {foreach from=$wallposts item=wallpost}