fix: clean up an orphaned etchosts directory for the container that failed to create

[haytok]

When specifying 22200-22299:22200-22299 for -p optinn in running nerdctl
run, the following errors occur.

$ nerdctl run --rm -p 22200-22299:22200-22299 alpine sh
FATA[0000] create container failed validation: containers.Labels: label key and value length (7714 bytes) greater than maximum size (4096 bytes), key: nerdctl/ports: invalid argument

This error is expected behavior in nerdctl.

However, the etchosts directory for this container has not been cleaned
up, even though the container has not been created.

Specifically, the following directory for the container remains without
being cleaned up.

$ ls ~/.local/share/nerdctl/1935db59/etchosts/default/
ea9c09bfdbc525db0b2cfdf3632ddf7c0e58918044acc626019f2fc4e1167573

Therefore, this PR creates the following three commits to clean up an
orphaned directory when the nerdctl run command fails to create a
container with an invalid value for the -p option.

1. Refactor TestRunWithInvalidPortThenCleanUp in
   cmd/nerdctl/container/container_run_network_linux_test.go based on the
   Principles in the following document

• https://github.com/containerd/nerdctl/tree/main/docs/testing#principles

2. Add the logic to clean up an orphaned etchosts directory for the
   container that failed to create

3. Add an test for added logic to TestRunWithInvalidPortThenCleanUp

[AkihiroSuda]

Thanks