Fix spelling of $add_ellipses is comment.

Problem/Motivation

In https://git.drupalcode.org/project/drupal/-/blob/11.x/core/lib/Drupal/Co... L300 there is a spelling error in a comment which refers to $add_ellipses - the correct variable to reference should be $add_ellipsis.

   * @param int $min_wordsafe_length
   *   If $wordsafe is TRUE, the minimum acceptable length for truncation (before
   *   adding an ellipsis, if $add_ellipsis is TRUE). Has no effect if $wordsafe
   *   is FALSE. This can be used to prevent having a very short resulting string
   *   that will not be understandable. For instance, if you are truncating the
   *   string "See myverylongurlexample.com for more information" to a word-safe
   *   return length of 20, the only available word boundary within 20 characters
   *   is after the word "See", which wouldn't leave a very informative string. If
   *   you had set $min_wordsafe_length to 10, though, the function would realise
   *   that "See" alone is too short, and would then just truncate ignoring word
   *   boundaries, giving you "See myverylongurl..." (assuming you had set
   *   $add_ellipses to TRUE).

Proposed resolution

Change $add_ellipses to $add_ellipsis