fix(Core/Loot): players can roll on unique items they already own (#8003)

Players should not be able to roll on items they already have.
This commit removes that.

- Closes https://github.com/azerothcore/azerothcore-wotlk/issues/7896

Co-authored-by: Skjalf <47818697+Nyeriah@users.noreply.github.com>

src/server/game/Loot/LootMgr.cpp

@@ -428,6 +428,14 @@ bool LootItem::AllowedForPlayer(Player const* player, bool isGivenByMasterLooter
         return false;
     }
 
+    // Checking for unique or unique(XX) objects
+    // master looter should still be able to see the loot to give to people.
+    // casting to avoid warnings, it's unlikely there's an item with unique but 2^31 items allowed.
+    if (!isMasterLooter && pProto->MaxCount > 0 && ((int32)player->GetItemCount(itemid, true) >= pProto->MaxCount))
+    {
+        return false;
+    }
+
     // not show loot for not own team
     if ((pProto->Flags2 & ITEM_FLAGS_EXTRA_HORDE_ONLY) && player->GetTeamId(true) != TEAM_HORDE)
     {