CBQE-0: remove extra verification for extract_remote_info

advantages:
once we get extract_remote_info per RemoteMachineShellConnection  session =>
less time,code, log output
don't need code like:
        if getattr(self, "info", None) is None:
            self.info = self.extract_remote_info()

Change-Id: I9681b82d9f10a50c7e5a7f4e8655c52b4af00b00
Reviewed-on: http://review.couchbase.org/35137
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>