Print testbench log on packetimpact failures
Print testbench log on packetimpact failures

These logs include flags passed to packetimpact tests (the Go tests), and test
failure messages.

PiperOrigin-RevId: 320989521

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor