Backported #6755 to 3-2-stable. Don't read csv file during executing db:fixtures:load.
Merge pull request #9485 from authorNari/backport-6755-to-3-2-stable

Backported #6755 to 3-2-stable. Don't read csv file during executing db:fixtures:load.

CSV fixtures have already been removed some time ago in 1716da07204193c8acf967e2d75a53a82e4c7c28, but the task was still loading them, even though later it tried to find the related yaml file.