feat!: remove ontobee search (#2632)

Author: jsstevenson

_includes/header.html

@@ -169,13 +169,6 @@
                     <a class="nav-link" href="/faq/index.html">FAQ</a>
                 </li>
             </ul>
-            <form class="d-flex" role="search" action="https://ontobee.org/search" method="get">
-                <!-- while the ontology input doesn't do anything, the Ontobee site is broken and doesn't work if it's missing -->
-                <input name="ontology" type="hidden" value=""/>
-                <input class="form-control me-2" type="search" placeholder="Search Ontobee" aria-label="Search"
-                       name="keywords">
-                <button class="btn btn-outline-success" type="submit">Search</button>
-            </form>
         </div>
     </div>
 </nav>