MDL-55564 output: Use template for password autofill hack

Part of MDL-55071

lib/templates/prevent_form_autofill_password.mustache

@@ -0,0 +1,23 @@
+{{!
+    This file is part of Moodle - http://moodle.org/
+
+    Moodle is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Moodle is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+}}
+{{!
+    Snippet to prevent browsers from autofilling password fields.
+}}
+<div class="hide">
+    <input type="text" class="ignoredirty" />
+    <input type="password" class="ignoredirty" />
+</div>

lib/weblib.php

@@ -3744,5 +3744,6 @@ function get_formatted_help_string($identifier, $component, $ajax = false, $a =
  * @return string HTML to prevent password autofill
  */
 function prevent_form_autofill_password() {
-    return '<div class="hide"><input type="text" class="ignoredirty" /><input type="password" class="ignoredirty" /></div>';
+    global $OUTPUT;
+    return $OUTPUT->render_from_template('core/prevent_form_autofill_password', []);
 }