pbl short tests runtime error

[pdziekan]

Since 3D sharedmem decomposition along the y axis ( #463), short pbl tests sometimes throw the "stuck in pressure solver" error.
Observed only for:

• Github Actions worker, not seen on other machines
• without MPI
• OMP_NUM_THREADS>2
• happens often for pbl_iles_short, rarely fo pbl_smg_short.

Currently short pbl tests are not ran on GA without MPI, because long version are ran.
Long version work correctly.