customvars.phtml: Show a customvar name as-is

Don't uppercase first, exchange `_` for spaces and lower everything else

resolves #3987

modules/monitoring/application/views/scripts/show/components/customvars.phtml

@@ -1,6 +1,6 @@
 <?php foreach ($object->customvars as $name => $value): ?>
 <tr>
-    <th><?= $this->escape(ucwords(str_replace('_', ' ', strtolower($name)))) ?></th>
+    <th><?= $this->escape($name) ?></th>
     <td class="custom-variables"><?= $this->customvar($value) ?></td>
 </tr>
 <?php endforeach ?>