test: Remove unused variable Failure

Commit 6ccda11a98afd6f4459e9ff1c24de4ad4450de23 removed its use but forgot to
remove it on this line.

Change-Id: I90375ce1e4b8e0b7e140df908323bc269e0baf40
diff --git a/src/osmo_gsm_tester/test.py b/src/osmo_gsm_tester/test.py
index 45ac602..2958501 100644
--- a/src/osmo_gsm_tester/test.py
+++ b/src/osmo_gsm_tester/test.py
@@ -35,7 +35,7 @@
 Timeout = None
 
 def setup(suite_run, _test, ofono_client, suite_module, event_module):
-    global trial, suite, test, resources, log, dbg, err, wait, wait_no_raise, sleep, poll, prompt, Failure, Timeout
+    global trial, suite, test, resources, log, dbg, err, wait, wait_no_raise, sleep, poll, prompt, Timeout
     trial = suite_run.trial
     suite = suite_run
     test = _test