Upon inspection I see that the target element already has text-overflow: ellipsis; applied as well, so it seems it is already redundant.
Use of jquery.autoEllipsis was removed from the main search suggest interface in 2014 (56a4aff8ca61106c; T61172). I was surprised that it was re-introduced in the OOjs UI version of the search suggestions on the Special:Search page.
I'd like to deprecate and remove this module from MediaWiki core. It seems the use of it in mw.widgets.TitleOptionWidget is the last one in all Wikimedia Git repos.