[2020] Stop spamming gas traps

Especially if someone has already built a trap tunnel on one side, do not add gas traps to the front of it and extend it all the way and spam it over the spawns.

This happened to me in a pl 140 rtl mission. I spent tons of mats and traps tunneling one side only to have a player come in late and just spam gas traps in front my tunnels. You are basically stealing all the combat score and now everyone else in the lobby won't get rewarded properly. There were other spawn points from other directions they could've trapped, but instead they put their traps in front of mine smh.