Core/Misc: Replace Time.UnixTime with GameTime.GetGameTime()

Port From (https://github.com/TrinityCore/TrinityCore/commit/e17e4e6f0700c7d950e1b2654c217ec8b28ae79e)

Source/Game/BlackMarket/BlackMarketEntry.cs

@@ -98,12 +98,12 @@ namespace Game.BlackMarket
 
         public uint GetSecondsRemaining()
         {
-            return (uint)(_secondsRemaining - (Time.UnixTime - Global.BlackMarketMgr.GetLastUpdate()));
+            return (uint)(_secondsRemaining - (GameTime.GetGameTime() - Global.BlackMarketMgr.GetLastUpdate()));
         }
 
         long GetExpirationTime()
         {
-            return Time.UnixTime + GetSecondsRemaining();
+            return GameTime.GetGameTime() + GetSecondsRemaining();
         }
 
         public bool IsCompleted()

Source/Game/BlackMarket/BlackMarketManager.cs

@@ -70,7 +70,7 @@ namespace Game.BlackMarket
                 return;
             }
 
-            _lastUpdate = Time.UnixTime; //Set update time before loading
+            _lastUpdate = GameTime.GetGameTime(); //Set update time before loading
 
             SQLTransaction trans = new();
             do
@@ -100,7 +100,7 @@ namespace Game.BlackMarket
         public void Update(bool updateTime = false)
         {
             SQLTransaction trans = new();
-            long now = Time.UnixTime;
+            long now = GameTime.GetGameTime();
             foreach (var entry in _auctions.Values)
             {
                 if (entry.IsCompleted() && entry.GetBidder() != 0)