Missing meshes for hom_euler test cases #2874

Describe the bug

21 of the 24 configs under SU2/TestCases/hom_euler/ cannot be run because their mesh files are absent from the TestCases repo.

TestCases/hom_euler/ contains only NACA0012_5thOrder, while SU2/TestCases/hom_euler/ has configs for Ringleb (7 variants), SubsonicChannel (3), InviscidVortex (3), Sphere_4thOrder_Hexa, Sphere_4thOrder_Tet, and NACA0012_3D_Hybrid_4thOrder. Note that hom_navierstokes is unaffected — its meshes are present in the TestCases repo as expected.

To reproduce:

git clone https://github.com/su2code/SU2.git
git clone https://github.com/su2code/TestCases.git
cd SU2/TestCases/hom_euler/Ringleb/Quad100X50_nPoly3
SU2_CFD Ringleb.cfg

gives:

The SU2 mesh file named Quad100X50_nPoly3.su2 was not found.

The same happens for all Ringleb, SubsonicChannel, Sphere and NACA0012_3D_Hybrid configs. Note these configs also use the deprecated REF_LENGTH_MOMENT, which needs replacing with REF_LENGTH before the mesh error is reached. The three InviscidVortex configs fail earlier with ITER must not be used when running multizone and/or unsteady problems, so they were not tested for the mesh issue.

I found this while working through configs that still use the deprecated EXT_ITER option (#2866). I left the hom_euler cases out of that PR because I can't verify them without the meshes.

Are these meshes available somewhere, or should these cases be removed?

Bug report checklist

• Consulting the build instructions (https://su2code.github.io/docs_v7/Build-SU2-Linux-MacOS/).
• Looking for similar problems on GitHub or CFD-Online (https://www.cfd-online.com/Forums/su2/).
• Updating to the newest version of SU2 (either develop, master, or the pre-built executables https://su2code.github.io/download.html).

Desktop (please complete the following information):

• OS: Fedora release 42 (Adams)
• C++ compiler and version: g++ (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7)
• MPI implementation and version: N/A (built with -Dwith-mpi=disabled)
• SU2 Version: 8.5.0 "Harrier", built from source on develop