Cleaning now useless LodelHook call and import

install/lodel_admin.py

     from lodel.settings.utils import SettingsError
     from lodel.leapi.leobject import LeObject
     from lodel.plugin import Plugin
-    from lodel.plugin.hooks import LodelHook
     from lodel import logger
 
-    LodelHook.call_hook('datasources_migration_init', __name__, None)
-
     ds_cls = dict() # EmClass indexed by rw_datasource
     for cls in dyncode.dynclasses:
         ds = cls._datasource_name