Add tests multicontainer start/stop
Add tests multicontainer start/stop

Each container has its respective gofer. Test that
gofer can be shutdown when a container stops and that
it doesn't affect other containers.

PiperOrigin-RevId: 220829898
Change-Id: I2a44a3cf2a88577e6ad1133afc622bbf4a5f6591

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