IMPALA-8413: Don't assume non-zero network counters in tests
IMPALA-8413: Don't assume non-zero network counters in tests

In virtualized test environments (e.g. docker) we have seen cases where
some of the network counters are still zero when the
system-state-info-test runs. This change adjusts the test to allow
counters to be zero, since other tests make sure that non-zero values
are parsed correctly.

Change-Id: I39e18510b1c20749e218748eaaffb74abeae4ebe
Reviewed-on: http://gerrit.cloudera.org:8080/13017
Reviewed-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>
Tested-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>
Reviewed-on: https://gerrit.sjc.cloudera.com/c/cdh/impala/+/49289
Tested-by: Jenkins User <d95b56ce41a2e1ac4cecdd398defd7414407cc08@cloudera.com>
CDH-Build: Jenkins User <d95b56ce41a2e1ac4cecdd398defd7414407cc08@cloudera.com>
Quasar-L0: quasar-precommit User
Reviewed-by: Lars Volker <4d73c29a4561048ce85fa0051bb7a6d201781159@cloudera.com>
Tested-by: Laszlo Gaal <57b770caf3b7d570ebf40813dac2ce5f53722fa7@cloudera.com>

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