chore: fallback echo defined nameserver

Update DNS configuration handling in entrypoint script.

docker/entrypoint.sh

@@ -221,8 +221,9 @@ set_envvars() {
 start_and_monitor() {
   printf "\n---------------------- STARTING CORE -----------------------\n"
 
-  # Regenerate the resolvconf
-  /usr/sbin/resolvconf -u
+  # Due to resolvconf resetting the DNS we echo back the one we defined (or fallback to default).
+  resolvconf -u
+  echo "nameserver ${global_dns}" >> /etc/resolv.conf
 
   # Due to some instances complaining about this, making sure its there every time.
   mkdir -p /dev/net