Fix startup parameter issue for samba version 4.15+

[gabriel-lando]

Replace parameter "S" from the "-FS" startup script to "--debug-stdout", as the "--log-stdout" parameter was replaced to "--debug-stdout" in smbd version 4.15+ as we can see here.

If we try to create a new docker image using the current dperson/samba repository and run it, the smbd service won't start. This PR fixes the startup issue caused by an inexistent parameter in the latest version, replacing it with its substitute parameter.