[Syphonicc]

Merge the duplicate nearfield nodes in euler/biparabolic/mesh_BIPARABOLIC_sup.su2. This goes with su2code/SU2#2865.

Why

The mesh was made of two blocks, the main domain and a strip below y = -2. They only touched on the nearfield line, where each block had its own copy of the 250 nodes (markers upper_nearfield / lower_nearfield). The nearfield BC that used to couple the two copies was removed from SU2 in 2021, so the blocks were no longer connected. Both sides of y = -2 became open boundaries, and the case produced non-physical points and diverged.

Change

• Merged the 250 coincident nodes: 56,831 → 56,581 points, and the elements are unchanged.
• Replaced the two nearfield markers with a single internal marker, nearfield (249 edges, all interior).
• Left airfoil and farfield unchanged.

With this mesh, the case's original settings (JST, CFL 25, MGLEVEL= 3) converge to rms[Rho] = -12 in about 510 iterations, with MARKER_NEARFIELD= ( nearfield ) and EQUIV_AREA= YES. Only euler/biparabolic/BIPARABOLIC.cfg uses this mesh.