hardware: tweak core and core-webui targets

given that relay, button and led settings may be hardcoded,
explicitly remove from -core and -core-webui
restore telnet debugging though, since the terminal output needs it

for -core-webui, disables mdns and the generic webui server + webui blob
per 56f74cfe, make the resulting .bin even smaller

code/espurna/telnet.cpp

@@ -19,6 +19,7 @@ Updated to use WiFiServer and support reverse connections by Niek van der Maas <
 
 #if TELNET_SUPPORT
 
+#include <list>
 #include <memory>
 #include <vector>