fix: load port service names CSV in netflow v5 test

The "Parse netflow v5 stream" test was missing the
IpPort::set_csv_iana_ports() call, making it depend on global static
state populated by sflow tests that happen to run first. When run in
isolation (e.g. --randomize-run-order or filtered by [netflow]), the
port map is empty so port 23 resolves to "23" instead of "telnet".

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: leoparente

src/handlers/flow/test_flows.cpp

@@ -408,6 +408,7 @@ TEST_CASE("Parse netflow v5 stream", "[netflow][flow]")
     FlowInputStream stream{"netflow-test"};
     stream.config_set("flow_type", "netflow");
     stream.config_set("pcap_file", "tests/fixtures/nf5.pcap");
+    visor::network::IpPort::set_csv_iana_ports("tests/fixtures/pktvisor-port-service-names.csv");
 
     visor::Config c;
     auto stream_proxy = stream.add_event_proxy(c);