Core/Battleground/SOTA: Initialize uninitialized variables.

Fixes:

==8111== Conditional jump or move depends on uninitialised value(s)
==8111==    at 0x12B542C: BattlegroundSA::FillInitialWorldStates(WorldPacket&) (BattlegroundSA.cpp:421)
==8111==    by 0xF93CD9: Player::SendInitWorldStates(unsigned int, unsigned int) (Player.cpp:9664)'

And similar.

src/server/game/Battlegrounds/Zones/BattlegroundSA.cpp

@@ -37,6 +37,11 @@ BattlegroundSA::BattlegroundSA()
     SignaledRoundTwo = false;
     SignaledRoundTwoHalfMin = false;
     InitSecondRound = false;
+
+    //! This is here to prevent an uninitialised variable warning
+    //! The warning only occurs when SetUpBattleGround fails though.
+    //! In the future this function should be called BEFORE sending initial worldstates.
+    memset(&GraveyardStatus, 0, sizeof(GraveyardStatus));
 }
 
 BattlegroundSA::~BattlegroundSA()