test: remove unreliable check from test_restart_both

The check arrived late when elections were already completed.
Circumstances are a bit weird. For some reason the check hang for two
seconds. Only after that it received conn refused, and during these two
seconds elections happened and leader was chosen so check can never
succeed after that.

test/int/test_couple.py

@@ -100,7 +100,6 @@ def test_restart_both(cluster2: Cluster):
 
     log.info("waiting for i2")
     i2.start()
-    Retriable(timeout=10, rps=10).call(check_alive, i2)
 
     # Speed up elections
     i2.promote_or_fail()