cryptocheck: Don't test Chacha20-Poly1305 with an IV size of 8

OpenSSL 3.0+ doesn't support an IV size of 8 either for the Chacha20
stream cipher or the AEAD combination with Poly1305. This did work
previously with OpenSSL 1.1.

Reviewed by: markj
Sponsored by: AFRL, DARPA
Differential Revision: https://reviews.freebsd.org/D45280