environment: Fix os.environ language setting.

A combination of ansible-freeipa modifications and a newer version of
IPA has brought a regression regarding different OS localization.

For properly setting environment to use "C" language, as required by
ansible-freeipa, the setting must be executed before importing the
module 'ipaserver.dcerpc', so setting environment language was moved
closer to the 'import os' statement, so that it is always set, as soon
as possible.

Note that 'import os' should always be imported before any FreeIPA
module.