Fix logic bugs in 2D Actuator Disk preprocessing and Periodic Solver

[shbhmexe]

This PR fixes logic bugs in the 2D Actuator Disk surface splitting code in CSU2ASCIIMeshReaderFVM.cpp:

1. Fix wrong loop variable: Changed ActDiskPoint_Front[iEdge] to ActDiskPoint_Front[iPoint] - was using wrong variable causing incorrect perimeter detection
2. Fix wrong array access: Changed EdgeBegin[...] to ActDiskPoint_Front[...] - was indexing wrong array causing potential segfault
3. Remove incorrect unique() call: The perimeter detection needs frequency information which unique() was destroying

Related Work

No related PRs or issues.

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.

[pcarruscag]

Do you have before/after results?

[shbhmexe]

Do you have before/after results?

No before/after numerical results available as this fixes 2D Actuator Disk code path which has no regression test coverage.

The changes are logical corrections:

Fix wrong variable iEdge → iPoint in loop
Fix wrong array EdgeBegin → ActDiskPoint_Front
Remove unique() that was destroying frequency info needed for perimeter detection
These would cause incorrect mesh splitting or segfaults for 2D actuator disk cases.

[shbhmexe]

and also check this pr #2669 and #2663

[pcarruscag]

You'll need to add a regression test for this.

[shbhmexe]

You'll need to add a regression test for this.

i add regression test for this particular fix

[bigfooted]

You'll need to add a regression test for this.

i add regression test for this particular fix

The su2 mesh goes into the repository su2code/Testcases
you can then test the regressions by modifying .github/workflow/regression.yml, change -c develop into -c fix_actuator_disk or whatever the branch in Testcases is called:

      # -t <Tutorials-branch> -c <Testcases-branch>
      args: -b ${{github.ref}} -t develop -c develop -s ${{matrix.testscript}}

[shbhmexe]

You'll need to add a regression test for this.

i add regression test for this particular fix

The su2 mesh goes into the repository su2code/Testcases you can then test the regressions by modifying .github/workflow/regression.yml, change -c develop into -c fix_actuator_disk or whatever the branch in Testcases is called:

      # -t <Tutorials-branch> -c <Testcases-branch>
      args: -b ${{github.ref}} -t develop -c develop -s ${{matrix.testscript}}

Done! I've:

Added test registration in serial_regression.py
Updated regression.yml to use -c fix_actuator_disk Will push mesh files to su2code/TestCases on fix_actuator_disk branch