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/Ninjitsu/ShadowJump.cs

@@ -92,8 +92,6 @@ public class Shadowjump : NinjaSpell, ISpellTargetingPoint3D
 
             Stealth.OnUse(m); // stealth check after the shadow jump
         }
-
-        FinishSequence();
     }
 
     public override bool CheckCast()
@@ -115,4 +113,4 @@ public class Shadowjump : NinjaSpell, ISpellTargetingPoint3D
         Caster.SendLocalizedMessage(1063088); // You prepare to perform a Shadowjump.
         Caster.Target = new SpellTargetPoint3D(this, TargetFlags.None, 11);
     }
-}
+}