Revert "Promote phutil-tag again"

This reverts commit 8fbabdc06d, reversing
changes made to 2dab1c1e42.

src/applications/macro/controller/PhabricatorMacroViewController.php

@@ -147,7 +147,7 @@ final class PhabricatorMacroViewController
       foreach ($subscribers as $subscriber) {
         $sub_view[] = $this->getHandle($subscriber)->renderLink();
       }
-      $sub_view = phutil_implode_html(', ', $sub_view);
+      $sub_view = array_interleave(', ', $sub_view);
     } else {
       $sub_view = phutil_tag('em', array(), pht('None'));
     }