[drop] engine torrentz: torrentz2.eu and torrentz2.is are offline

[1] https://torrentfreak.com/torrentz2-eu-domain-suspended-by-registry-on-public-prosecutors-order-200628/

Suggested-by: @rasos https://github.com/searx/searx/issues/1875#issuecomment-877755872


Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>