VNC: use display 12 and remove user password

docker/vnc/Dockerfile

@@ -13,10 +13,11 @@ RUN --mount=type=cache,sharing=locked,target=/var/cache/apt --mount=type=cache,s
     x11-apps \
     xfce4
 
-EXPOSE 5901
+EXPOSE 5912
 
 RUN chmod 777 /usr/share/novnc/utils \
  && useradd -m user \
+ && sed -i '/user/s/:x:/::/' /etc/passwd \
  && echo "user ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 
 USER user

docker/vnc/docker-vnc

@@ -2,6 +2,6 @@
 
 mkdir ~/.vnc
 ln -s /usr/bin/startxfce4 ~/.vnc/xstartup
-tigervncserver -SecurityTypes None
-sed -i 's/.(hostname)/localhost/g;s/5900/5901/' /usr/share/novnc/utils/launch.sh
+tigervncserver -SecurityTypes None :12
+sed -i 's/.(hostname)/localhost/g;s/5900/5912/' /usr/share/novnc/utils/launch.sh
 /usr/share/novnc/utils/launch.sh