Automatic merge from submit-queue (batch tested with PRs 49328, 49285, 49307, 49127, 49163)
kubeadm: don't customize etcd selinux label
The original change that added the unconfined label included a comment
indicating it won't be needed in the future.
See: https://github.com/kubernetes/kubernetes/pull/33555#issuecomment-251126908
That time is now. https://github.com/kubernetes/kubernetes/pull/33663
has landed and means we no longer have to go out of our way to make that
work.
Removing the label also increases security since there wasn't really a
good reason for etcd to be run with such broad selinux privileges.
This also will allow kubeadm to avoid errors on distros without an spc_t
type, such as Gentoo and Container Linux (at the time of writing at
least).
Fixes https://github.com/kubernetes/kubeadm/issues/269
**Release note**:
```release-note
NONE
```
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