iotests.py: pause_job(): drop return value

The returned value is unused. It's simple to check by command

 git grep -B 3 '\.pause_job('

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20231006154125.1068348-13-vsementsov@yandex-team.ru
Signed-off-by: John Snow <jsnow@redhat.com>

tests/qemu-iotests/iotests.py

@@ -1338,8 +1338,7 @@ def pause_job(self, job_id='job0', wait=True):
         result = self.vm.qmp('block-job-pause', device=job_id)
         self.assert_qmp(result, 'return', {})
         if wait:
-            return self.pause_wait(job_id)
-        return result
+            self.pause_wait(job_id)
 
     def case_skip(self, reason):
         '''Skip this test case'''