OpenSSH: Prefer AES-GCM ciphers over AES-CTR

OpenSSH: Prefer AES-GCM ciphers over AES-CTR

This reflects the following change made upstream in OpenSSH 9.9:

 * ssh(1): prefer AES-GCM to AES-CTR mode when selecting a cipher
   for the connection. The default cipher preference list is now
   Chacha20/Poly1305, AES-GCM (128/256) followed by AES-CTR
   (128/192/256).

However, we keep preferring AES-GCM over Chacha/Poly, as hardware
acceleration often grants the former a better performance, while there
is no security advance of Chacha/Poly usage over 256 bit AES-GCM.

Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>