fix: Fixes double calls with Target cancel and spell sequences (#1840)

### Summary
- Cleans up target cancellation being called incorrectly.
- An invalid target type (which should never happen), now calls `OnTargetUntargetable` instead of `OnTargetCanceled`
- Removes double calls to `FinishSequence` in Spells.

Projects/UOContent/Spells/Spellweaving/GiftOfLife.cs

@@ -68,8 +68,6 @@ namespace Server.Spells.Spellweaving
 
                 BuffInfo.AddBuff(m, new BuffInfo(BuffIcon.GiftOfLife, 1031615, 1075807, duration, m, null, true));
             }
-
-            FinishSequence();
         }
 
         public static void Initialize()

Projects/UOContent/Spells/Spellweaving/GiftOfRenewal.cs

@@ -65,8 +65,6 @@ namespace Server.Spells.Spellweaving
                     );
                 }
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()

Projects/UOContent/Spells/Spellweaving/NatureFury.cs

@@ -51,8 +51,6 @@ namespace Server.Spells.Spellweaving
 
                 new InternalTimer(nf).Start();
             }
-
-            FinishSequence();
         }
 
         public override bool CheckCast()

Projects/UOContent/Spells/Spellweaving/WordOfDeath.cs

@@ -68,8 +68,6 @@ namespace Server.Spells.Spellweaving
 
                 SpellHelper.Damage(this, m, damage, 0, 0, 0, 0, 0, 100);
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()