Fix deletion of deprecated notes

Notes in Snippets / Commits are deleted from the DOM even before the
user confirmed the deletion. With `bootstrap_confirmation_modals`
enabled this actually caused a bug, because the element is
progamatically clicked after confirmation. But as the element is removed
from the DOM already, Rails/UJS didn't intercept the click properly.

If we switch from a click handler to an ajax:success handler _and_
remove the note from the DOM after a successful deletion, this problem
is resolved.

app/assets/javascripts/deprecated_notes.js

@@ -143,7 +143,7 @@ export default class Notes {
     // resolve a discussion
     this.$wrapperEl.on('click', '.js-comment-resolve-button', this.postComment);
     // remove a note (in general)
-    this.$wrapperEl.on('click', '.js-note-delete', this.removeNote);
+    this.$wrapperEl.on('ajax:success', '.js-note-delete', this.removeNote);
     // delete note attachment
     this.$wrapperEl.on('click', '.js-note-attachment-delete', this.removeAttachment);
     // update the file name when an attachment is selected
@@ -188,7 +188,7 @@ export default class Notes {
   cleanBinding() {
     this.$wrapperEl.off('click', '.js-note-edit');
     this.$wrapperEl.off('click', '.note-edit-cancel');
-    this.$wrapperEl.off('click', '.js-note-delete');
+    this.$wrapperEl.off('ajax:success', '.js-note-delete');
     this.$wrapperEl.off('click', '.js-note-attachment-delete');
     this.$wrapperEl.off('click', '.js-discussion-reply-button');
     this.$wrapperEl.off('click', '.js-add-diff-note-button');
@@ -827,6 +827,8 @@ export default class Notes {
    */
   removeNote(e) {
     const $note = $(e.currentTarget).closest('.note');
+
+    $note.one('ajax:complete', () => {
       const noteElId = $note.attr('id');
       $(`.note[id="${noteElId}"]`).each((i, el) => {
         // A same note appears in the "Discussion" and in the "Changes" tab, we have
@@ -871,6 +873,7 @@ export default class Notes {
 
       Notes.checkMergeRequestStatus();
       return this.updateNotesCount(-1);
+    });
   }
 
   /**