How to avoid Firefox Survey in automated tests?

Hello, I have problem with Firefox 56 on macOS. After a week from the last update, browser started to show a toolbar "The Firefox team is interested in learning what brings you to Firefox today". Also, some time after starting (exactly 4:30) it opens a new tab with qsurvey.mozilla.com URL. It's a problem, because we use Firefox to run automated tests, and when a new foreground tab opens, browser will suspend test execution in background tab. I was unable to upload a screenshot, so there is a screencast link: https://devexpress-my.sharepoint.com/personal/andrey_belym_devexpress_com/_layouts/15/guestaccess.aspx?docid=045ca75f312254839a72a786974495ba6&authkey=AeNiHiZtgNOXBT5zAztJb_s, rewind it to 4:30 to see the toolbar and the survey. Maybe there is something in about:config that can prevent it from showing?