ssh-server: use new drop-in configuration on bullseye

ssh-server/files/ssh_config

ssh-server/files/ssh_config.d/gssapi.conf

ssh-server/files/ssh_config.d/sshfp.conf

ssh-server/tasks/main.yml

ssh-server/templates/sshd_config.d/authentication.conf.j2

ssh-server/templates/sshd_config.d/banner.conf.j2

ssh-server/templates/sshd_config.d/ciphers.conf.j2

ssh-server/templates/sshd_config.d/forwarding.conf.j2

ssh-server/templates/sshd_config.d/groups.conf.j2

ssh-server/templates/sshd_config_main.j2

ssh-server/templates/sshd_config_old_style.j2