Sanitize label ends in hyphen, underbar, and dot

[and-es]

Fixes #3663

The error occurs because a label must start and end with an alphanumeric character in kubernetes(see: https://github.com/kubernetes/kubernetes/blob/9b7a839bde763575af3406158115b16cff513274/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L166)