test(test_network_latency): dump metrics on ping failure

Looking at Firecracker metrics may help us understand the origin of the
issue where a ping attempt fails.

Signed-off-by: Nikita Kalyazin <[email protected]>

Author: kalyazin

tests/integration_tests/performance/test_network_ab.py

@@ -79,7 +79,11 @@ def test_network_latency(network_microvm, metrics):
             f"ping -c {request_per_round} -i {delay} {host_ip}"
         )
 
-        samples.extend(consume_ping_output(ping_output, request_per_round))
+        try:
+            samples.extend(consume_ping_output(ping_output, request_per_round))
+        except AssertionError:
+            network_microvm.flush_metrics()
+            raise
 
     for sample in samples:
         metrics.put_metric("ping_latency", sample, "Milliseconds")