BUG/MINOR: quic: Wrong key update cipher context initialization for encryption

BUG/MINOR: quic: Wrong key update cipher context initialization for encryption

As noticed by Miroslav, there was a typo in quic_tls_key_update() which lead
a cipher context for decryption to be initialized and used in place of a cipher
context for encryption. Surprisingly, this did not prevent the key update
from working. Perhaps this is due to the fact that the underlying cryptographic
algorithms used by QUIC are all symetric algorithms.

Also modify incorrect traces.

Must be backported in 2.6 and 2.7.