fix(Core/Spells): correct teleport distance for Shadowstep/Killing Spree/Warp (#10081)

- Closes #9345

src/server/game/Spells/Spell.cpp

@@ -1489,6 +1489,11 @@ void Spell::SelectImplicitTargetDestTargets(SpellEffIndex effIndex, SpellImplici
                 dist *= float(rand_norm());
             }
 
+            if (targetType.GetTarget() == TARGET_DEST_TARGET_BACK)
+            {
+                dist += target->GetFloatValue(UNIT_FIELD_BOUNDINGRADIUS);
+            }
+
             Position pos = dest._position;
             target->MovePositionToFirstCollision(pos, dist, angle);