If you had the geometry saved, e.g. as .stl file, then you could just pass some constraints to the delunayTriangulation. However, a small problem is that your edges are not straight, so it becomes difficult to define cornerpoints.
Here's another method you could try:
xyz = readmatrix('mesh data.xlsx');
[x,y,z] = deal(xyz(:,1),xyz(:,2),xyz(:,3))
% alphashape to get tight boundary without holes
shp = alphaShape(x,y,'holethreshold',1e5);
% plot edges
edges = boundaryFacets(shp);
plot(x(edges),y(edges),'k','linewidth',2);hold on
%get connectivity
tri = alphaTriangulation(shp);
t = trisurf(tri,x,y,z);
t.EdgeColor = 'none'
view(2)
