Retire DZE_MissionLootTable variable

AFAIK there is no performance difference between configFile and
missionConfigFile.

Using missionConfigFile by default simplifies loot scripts and makes the
extra config variable unnecessary. It's one less step for admins to
customize their tables.

SQF/dayz_code/Configs/CfgLoot/README.txt

@@ -1,6 +1,8 @@
-To use DZE_MissionLootTable = true; copy this CfgLoot folder to your mission.
+To customize the loot tables copy this CfgLoot folder to your mission.
 
-Then in description.ext add at the top:
+Then in description.ext replace this line:
+#include "\z\addons\dayz_code\Configs\CfgLoot\CfgLoot.hpp"
+with this:
 #include "CfgLoot\CfgLoot.hpp"