Add log during process wait in tests
Add log during process wait in tests

TestMultiContainerKillAll timed out under --race. Without logging,
we cannot tell if the process list is still increasing, but slowly,
or is stuck.

PiperOrigin-RevId: 297158834

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