EventLoop: Fix log error "Origin parent loop" during wait()

Setting the log.ctx manually is not needed anymore and it's actually
harmful since all palces where it was used, a log.Origin already in path
was being passed, causing a origin loop.

Change-Id: I0511b9f7bc59e3c7f2269ff3155d0c95db58d063
diff --git a/src/osmo_gsm_tester/obj/esme.py b/src/osmo_gsm_tester/obj/esme.py
index 13e1bba..cd416ab 100644
--- a/src/osmo_gsm_tester/obj/esme.py
+++ b/src/osmo_gsm_tester/obj/esme.py
@@ -190,7 +190,7 @@
             umref, self.pdus_pending = self.sms_send(sms_obj, mode, receipt)
             self.dbg('pdus_pending:', self.pdus_pending)
             self.client.set_message_sent_handler(self._process_pdus_pending)
-            MainLoop.wait(self, lambda: len(self.pdus_pending) == 0, timeout=10)
+            MainLoop.wait(lambda: len(self.pdus_pending) == 0, timeout=10)
             return umref
         finally:
             self.client.set_message_sent_handler(old_func)