Automatic merge from submit-queue (batch tested with PRs 67571, 67284, 66835, 68096, 68152). If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md.

cloudprovider: aws: return true on existence check for stopped instances

xref https://bugzilla.redhat.com/show_bug.cgi?id=1559271
xref https://github.com/openshift/origin/issues/19899

background https://github.com/kubernetes/kubernetes/pull/45986#issuecomment-386332055

Basically our customers are hitting this issue where the Node resource is deleted when the AWS instances stop (not terminate).  If the instances restart, the Nodes lose any labeling/taints.

Openstack cloudprovider already made this change https://github.com/kubernetes/kubernetes/pull/59931

fixes https://github.com/kubernetes/kubernetes/issues/45118 for AWS

**Reviewer note**: valid AWS instance states are `pending | running | shutting-down | terminated | stopping | stopped`.  There might be a case for returning `false` for instances in `pending` and/or `terminated` state.  Discuss!

`InstanceID()` changes from https://github.com/kubernetes/kubernetes/pull/45986 credit @rrati 

@derekwaynecarr @smarterclayton @liggitt @justinsb @jsafrane @countspongebob