ci: fix flaky test "update memory vs CheckBeforeUpdate"

This test fails in CI sometimes with the following error:

> `testcontainer test_update stopped' failed

Give OOM killer some time to do its job.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/integration/update.bats

@@ -854,5 +854,5 @@ EOF
 	# The container will be OOM killed, and runc might either succeed
 	# or fail depending on the timing, so we don't check its exit code.
 	runc update test_update --memory 1024
-	testcontainer test_update stopped
+	wait_for_container 10 1 test_update stopped
 }