refactor: Clean navigator state creation (#4070)

Minor change - cleans out the navigator state creation a bit

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- **Refactor**
  - Streamlined the navigation state initialization by consolidating how certain key attributes are set. This update improves consistency and clarity in the navigation process.
  
- **Tests**
  - Updated unit tests to align with the revised state initialization, ensuring reliable verification of navigation behavior.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Core/include/Acts/Propagator/Navigator.hpp

@@ -226,8 +226,6 @@ class Navigator {
 
   State makeState(const Options& options) const {
     State state(options);
-    state.startSurface = options.startSurface;
-    state.targetSurface = options.targetSurface;
     return state;
   }
 
@@ -279,6 +277,9 @@ class Navigator {
 
     state.reset();
 
+    state.startSurface = state.options.startSurface;
+    state.targetSurface = state.options.targetSurface;
+
     // Fast Navigation initialization for start condition:
     // - short-cut through object association, saves navigation in the
     // - geometry and volume tree search for the lowest volume

Core/include/Acts/Propagator/TryAllNavigator.hpp

@@ -161,6 +161,9 @@ class TryAllNavigatorBase {
 
     ACTS_VERBOSE("initialize");
 
+    state.startSurface = state.options.startSurface;
+    state.targetSurface = state.options.targetSurface;
+
     const TrackingVolume* startVolume = nullptr;
 
     if (state.startSurface != nullptr &&
@@ -261,9 +264,6 @@ class TryAllNavigator : public TryAllNavigatorBase {
 
   State makeState(const Options& options) const {
     State state(options);
-    state.startSurface = options.startSurface;
-    state.targetSurface = options.targetSurface;
-
     return state;
   }
 

Tests/UnitTests/Core/Propagator/NavigatorTests.cpp

@@ -188,8 +188,8 @@ BOOST_AUTO_TEST_CASE(Navigator_status_methods) {
     const TrackingVolume* startVol =
         tGeometry->lowestTrackingVolume(tgContext, position);
     const Layer* startLay = startVol->associatedLayer(tgContext, position);
-    state.startSurface = startSurf;
-    state.targetSurface = startSurf;
+    state.options.startSurface = startSurf;
+    state.options.targetSurface = startSurf;
     navigator.initialize(state, position, direction, Direction::Forward());
     BOOST_CHECK(testNavigatorStateVectors(state, 0u, 0u, 0u));
     BOOST_CHECK(testNavigatorStatePointers(state, startVol, startLay, startSurf,
@@ -208,7 +208,7 @@ BOOST_AUTO_TEST_CASE(Navigator_status_methods) {
 
     ACTS_INFO("    b) Initialise having a start surface");
     state = navigator.makeState(options);
-    state.startSurface = startSurf;
+    state.options.startSurface = startSurf;
     navigator.initialize(state, position, direction, Direction::Forward());
     BOOST_CHECK(testNavigatorStateVectors(state, 0u, 0u, 0u));
     BOOST_CHECK(testNavigatorStatePointers(state, startVol, startLay, startSurf,