feat(routes): add function to remove segments till end

lib/transport_helper.dart

@@ -140,6 +140,11 @@ class Route {
     segments.removeLast();
   }
 
+  void removeSegmentsTillEnd(int idx) {
+    segments.removeRange(idx, segments.length - 1);
+    dbDeleteTrailingRouteSegments(idx);
+  }
+
   void _removeSegment(int idx) {
     segments.removeAt(idx);
   }
@@ -287,7 +292,7 @@ class Route {
     );
   }
 
-  void dbDeleteTrailingRouteSegment(int position) {
+  void dbDeleteTrailingRouteSegments(int position) {
     Database database = DbHelper.db;
     if (position <= segments.length) {
       database.delete(