specify container name "main" to account for sidecar containers

[jaredstehler]

When running with injected sidecars (i.e. istio-proxy) pod.GetLogs requires a container name to be specified.

From https://pkg.go.dev/k8s.io/api/core/v1#PodLogOptions:

type PodLogOptions struct {
	metav1.TypeMeta `json:",inline"`

	// The container for which to stream logs. Defaults to only container if there is one container in the pod.
	// +optional
	Container string `json:"container,omitempty" protobuf:"bytes,1,opt,name=container"`

[regadas]

Thanks @jaredstehler !