Sorry -- there isn't an option to turn "tooltips" text off, and you're the first I've heard who asked about it.
There is a way to turn off "extended tooltips" though. Control-click the search column header to get at it. See attached
You can post a feature request in
https://www.gnutellaforums.com/new-feature-requests/
(oh, and you can edit your post to delete the attachment in case it contains problem filenames)