main/fail2ban: adjust filter for openssh 9.8

Upstream changes: https://github.com/fail2ban/fail2ban/compare/59c5e78ce90a49a6f5fb325d35199923c9c65f7c..50ff131a0fd8f54fdeb14b48353f842ee8ae8c1a

I think upstream made the -session suffix optional for compatibility with pre-9.8 sshd, which we need not.

fix #16287 (closed)