main/samba: don't do recursive logrotate

The /var/log/samba/log.* also matches rotated log files, making it a potential never-ending recursive mess.

Note that the current config logs to /var/log/samba/*.log, but the recursive pattern will still match when a client named "log" connects to a share (into /var/log/samba/log.log).

Note that this is not an issue with the default smbd and logrotate configs, since logrotate requires >1MB to rotate, and smbd self-rotates at 50KB.