notmuch-search-insert-authors now sets the evaporate property on the
ellipsis overlays. Emacs will delete them when the buffer contents
are zeroed out, which happens with `notmuch-refresh-buffer`. This
prevents them from being collapsed to zero-width overlays in position
1. See Emacs bug#58479. An upcoming change in Emacs will make these
dangling overlays visible to the user.