remove cloud encryption card

"Encryption with 7zip" is dangerously misleading and we have alternative cards that describe reasonable other ways to get the files encrypted and uploaded (cryptomator, or the exchange channel cards that actually describe valid PGP workflows). I think it's OK to just remove this. Comments welcome.

requested review from @vilem.ded

assigned to @miroslav.kratochvil

approved this merge request

mentioned in commit a42f9333

merged