[MD settings] using h2 for sub-headers consistently.

chrome/browser/resources/settings/search_engines_page/search_engine_entry.css

 /* Copyright (c) 2015 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 .favicon-image {
   -webkit-margin-end: 8px;
   background-repeat: no-repeat;
   background-size: contain;
   display: inline-block;
   height: 20px;
   vertical-align: middle;
   width: 20px;
 }
 
 .name {
   margin: auto;
 }
 
-#container {
-  border-top: 1px solid lightgray;
-  display: flex;
-  padding: 2px 0;
-}
-
 .dropdown-content {
   background: white;
   box-shadow: 0 2px 6px grey;
 }
 
 paper-icon-button {
   -webkit-padding-end: 0;
-  padding-bottom: var(--search-engines-list-item-vertical-space);
-  padding-top: var(--search-engines-list-item-vertical-space);
 }