Re-enable test on mpc memory cycling

[EtienneAr]

When used in MPC fashion, Aligator 0.15 output NaNs. A workaround was to use the branch temporaty_fix of alligator fork.
However, the CI still rely on the conda-forge version of Aligator, so the test failed. Thus, the test has been temporarily commented out.

Several solutions possible (from most ideal to least ideal) :

• Fix Aligator memory cycling in main
• Modify the ci to build aligator from source ?
• Edit slightly the ci workflow for it to skip the mpc test, but do not comment it out (for local users)