fix: Avoid creating an unnecessary syslog socket for Postfix (#3134)

Co-authored-by: Georg Lauterbach <44545919+georglauterbach@users.noreply.github.com>

target/postfix/master.cf

@@ -75,3 +75,4 @@ virtual        unix  -       n       n       -       -       virtual
 lmtp           unix  -       -       n       -       -       lmtp
 anvil          unix  -       -       n       -       1       anvil
 scache         unix  -       -       n       -       1       scache
+postlog  unix-dgram  n       -       n       -       1       postlogd

target/scripts/build/packages.sh

@@ -37,6 +37,9 @@ function _install_postfix
   chmod +x /bin/hostname
   apt-get "${QUIET}" install --no-install-recommends postfix
   mv /bin/hostname.bak /bin/hostname
+
+  # Irrelevant - Debian's default `chroot` jail config for Postfix needed a separate syslog socket:
+  rm /etc/rsyslog.d/postfix.conf
 }
 
 function _install_packages