Remove unnecessary track mapping code

This code was conflicting with the newly reimplemented function Staff::getLinkedTrackInStaff. The logic that these pieces of code were trying to handle is now all handled (as it should) in one single place.

src/engraving/dom/edit.cpp

@@ -5761,18 +5761,7 @@ void Score::undoChangeVisible(EngravingItem* item, bool visible)
 void Score::undoAddElement(EngravingItem* element, bool addToLinkedStaves, bool ctrlModifier, EngravingItem* elementToRelink)
 {
     Staff* ostaff = element->staff();
-    track_idx_t strack = muse::nidx;
-    if (ostaff) {
-        strack = ostaff->idx() * VOICES + element->track() % VOICES;
-
-        if (mu::engraving::Excerpt* excerpt = ostaff->score()->excerpt()) {
-            const TracksMap& tracks = excerpt->tracksMapping();
-
-            if (!tracks.empty() && strack != muse::nidx) {
-                strack = muse::key(tracks, strack, muse::nidx);
-            }
-        }
-    }
+    track_idx_t strack = element->track();
 
     ElementType et = element->type();
 
@@ -6431,15 +6420,6 @@ void Score::undoAddCR(ChordRest* cr, Measure* measure, const Fraction& tick)
 
     Staff* ostaff = cr->staff();
     track_idx_t strack = ostaff->idx() * VOICES + cr->voice();
-    // If this is on an excerpt, get actual track
-    if (mu::engraving::Excerpt* excerpt = ostaff->score()->excerpt()) {
-        if (ostaff->isVoiceVisible(cr->voice())) {
-            const TracksMap& tracks = excerpt->tracksMapping();
-            if (!tracks.empty()) {
-                strack = muse::key(tracks, strack, muse::nidx);
-            }
-        }
-    }
 
     SegmentType segmentType = SegmentType::ChordRest;