Migrate PySS adaptator to unmaintained code folder

The common_pyss_adaptator module is only used by unmaintained code, we
do not aim at maintaining it anymore.

schedulers/unMaintained/easyBackfillNotopo.py

 from batsim.batsim import BatsimScheduler
-from schedulers.common_pyss_adaptator import CpuSnapshot
 from sortedcontainers import SortedSet
 from procset import ProcSet
 
+from common_pyss_adaptator import CpuSnapshot
+
 class EasyBackfillNotopo(BatsimScheduler):
     """
     An EASY backfill scheduler that doesn't care about topology.