Do not generate id on C# side

Author: aurimasc

com.unity.mobile.notifications/Runtime/Android/AndroidNotificationCenter.cs

@@ -680,12 +680,9 @@ public static int SendNotification(AndroidNotification notification, string chan
             if (!Initialize())
                 return -1;
 
-            // Now.ToString("yyMMddHHmmssffffff"), but avoiding any culture-related formatting or dependencies
-            var now = DateTime.UtcNow;
-            var nowFormatted = $"{now.Year}{now.Month}{now.Day}{now.Hour}{now.Minute}{now.Second}{now.Millisecond}";
-            int id = Math.Abs(nowFormatted.GetHashCode()) + (new System.Random().Next(10000));
-            using (var builder = CreateNotificationBuilder(id, notification, channelId))
-                SendNotification(builder);
+            int id;
+            using (var builder = CreateNotificationBuilder(notification, channelId))
+                SendNotification(builder, out id);
 
             return id;
         }