fix: Fixes timer index offset (#1907)

### Summary

- Fixes timer intervals not continuing
- Fixes `Timer.Index` being off by 1. Should start at 0 for the first OnTick
- Simplifies Gift of Renewal end check
- Fixes force of nature not applying at the proper time and simplifies the timer logic.

Projects/Server/Timer/Timer.cs

@@ -70,7 +70,6 @@ public partial class Timer
     public TimeSpan Interval { get; set; }
     public int Index { get; private set; }
     public int Count { get; private set; }
-    public int RemainingCount => Count - Index;
     public bool Running { get; private set; }
 
     public TimerProfile GetProfile() => !Core.Profiling ? null : TimerProfile.Acquire(ToString() ?? "null");