MDL-77618 admin: Passwords should not auto complete

admin/templates/setting_configpasswordunmask.mustache

@@ -52,6 +52,7 @@
     <span data-passwordunmask="wrapper" data-passwordunmaskid="{{ id }}">
         <span data-passwordunmask="editor">
             <input  type="password"
+                    autocomplete="new-password"
                     name="{{ name }}"
                     id="{{ id }}"
                     value="{{ value }}"