sink particles at coarse levels cause problems

**Describe the bug** A run with sink particles and `amr.max_level > 0` may cause mass inconservation when there are sink particles at coarse levels. To enforce sink particles at finest level and fix this bug, we should enforce `setForceFinestLevel(true)` on sink particles and also set `amr.n_error_buf = 4` and `amr.grid_eff = 0` .