Core/Players: Implement generic SendClearFocus instead of magic SMSG_BREAK_PACKET randomly in the middle of code. Also preallocate correct size for packed guid.

src/server/game/Entities/Player/Player.cpp

@@ -24531,3 +24531,10 @@ void Player::_SaveInstanceTimeRestrictions(SQLTransaction& trans)
         trans->Append(stmt);
     }
 }
+
+void Player::SendClearFocus(Unit* target)
+{
+    WorldPacket data(SMSG_BREAK_TARGET, target->GetPackGUID().size());
+    data.append(target->GetPackGUID());
+    GetSession()->SendPacket(&data);
+}

src/server/game/Entities/Player/Player.h

@@ -2281,6 +2281,7 @@ class Player : public Unit, public GridObject<Player>
 
         void SendCinematicStart(uint32 CinematicSequenceId);
         void SendMovieStart(uint32 MovieId);
+        void SendClearFocus(Unit* target);
 
         /*********************************************************/
         /***                 INSTANCE SYSTEM                   ***/

src/server/game/Entities/Unit/Unit.cpp

@@ -16411,9 +16411,7 @@ void Unit::EnterVehicle(Vehicle *vehicle, int8 seatId, AuraApplication const * a
         WorldPacket data(SMSG_ON_CANCEL_EXPECTED_RIDE_VEHICLE_AURA, 0);
         thisPlr->GetSession()->SendPacket(&data);
 
-        data.Initialize(SMSG_BREAK_TARGET, 7);
+        thisPlr->SendClearFocus(vehicle->GetBase());
-        data.append(vehicle->GetBase()->GetPackGUID());
-        thisPlr->GetSession()->SendPacket(&data);
     }
 
     SetControlled(true, UNIT_STAT_ROOT);