Automatic merge from submit-queue (batch tested with PRs 41857, 41864, 40522, 41835, 41991)
kubeadm: update token separator to '.'
**What this PR does / why we need it**: From SIG meetings, it was agreed upon to have '.' be the separator for tokens. This PR updates that.
**Special notes for your reviewer**: /cc @luxas @jbeda
**Release note**:
```release-note
NONE
```