bug: envd bootstrap can't find buildkitd if it was stopped

[Triple-Z]

Description

envd bootstrap gets error if the envd_buildkitd was stopped before.

Reproduction

1. Stop the envd_buildkitd container.
2. Run the envd bootstrap.

Additional Info

None.

[gaocegege]

We just need to update code here

https://github.com/tensorchord/envd/blob/main/pkg/docker/docker.go#L273

+	// Add logic to check if the container is stopped.
	resp, err := g.ContainerCreate(ctx, config, hostConfig, nil, nil, name)
	if err != nil {
		return "", errors.Wrap(err, "failed to create container")
	}

	for _, w := range resp.Warnings {
		logger.Warnf("run with warnings: %s", w)
	}

	if err := g.ContainerStart(ctx, resp.ID, types.ContainerStartOptions{}); err != nil {
		return "", errors.Wrap(err, "failed to start container")
	}

[Triple-Z]

close due to #417 has merged.