Automatic merge from submit-queue (batch tested with PRs 59927, 59989, 59950). 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>.

cluster/images/hyperkube: Fix typo in Dockerfile for aggregator symlink

**What this PR does / why we need it**: Fixes typo in the hyperkube Dockerfile for kube-aggregator