Automatic merge from submit-queue (batch tested with PRs 56344, 56473). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Fix typo in component name of prometheus-to-sd config.

Fixes https://github.com/GoogleCloudPlatform/k8s-stackdriver/issues/70
```release-note
NONE
```