[alembic] Don't load config from Alembic env.py

Alembic is ran from koschei-admin wrapper, which is responsible for
loading up config -- there is no need to load config for the second
time.

alembic/env.py

@@ -1,11 +1,8 @@
 from alembic import context
 from logging.config import fileConfig
 
-from koschei.config import load_config
 from koschei.db import Base, grant_db_access, get_engine
 
-load_config(['/usr/share/koschei/config.cfg', '/etc/koschei/config-admin.cfg'])
-
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.
 config = context.config