Simplify vertical axis binning

NumbericAxis::createBinBoundaries and BinEdgeAxis::createBinBoundaries
both do the expected binning correctly.

Re #24492

Framework/Algorithms/src/Rebin2D.cpp

@@ -77,7 +77,7 @@ void Rebin2D::init() {
 void Rebin2D::exec() {
   // Information to form input grid
   MatrixWorkspace_const_sptr inputWS = getProperty("InputWorkspace");
-  NumericAxis *oldAxis2 = dynamic_cast<API::NumericAxis *>(inputWS->getAxis(1));
+  const NumericAxis *oldAxis2 = dynamic_cast<API::NumericAxis *>(inputWS->getAxis(1));
   if (!oldAxis2) {
     throw std::invalid_argument(
         "Vertical axis is not a numeric axis, cannot rebin. "
@@ -87,16 +87,9 @@ void Rebin2D::exec() {
   const auto &oldXEdges = inputWS->x(0);
   const size_t numXBins = inputWS->blocksize();
   const size_t numYBins = inputWS->getNumberHistograms();
-  std::vector<double> oldYEdges;
-  if (numYBins == oldAxis2->length()) {
-    // Pt data on axis 2, create bins
-    oldYEdges = oldAxis2->createBinBoundaries();
-  } else {
-    oldYEdges.resize(oldAxis2->length());
-    for (size_t i = 0; i < oldAxis2->length(); ++i) {
-      oldYEdges[i] = (*oldAxis2)(i);
-    }
-  }
+  // This will convert plain NumericAxis to bin edges while
+  // BinEdgeAxis will just return its edges.
+  const std::vector<double> oldYEdges = oldAxis2->createBinBoundaries();
 
   // Output grid and workspace. Fills in the new X and Y bin vectors
   // MantidVecPtr newXBins;