Automatic merge from submit-queue (batch tested with PRs 62655, 61711, 59122, 62853, 62390). 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>.

kubeadm: Mount additional paths inside apiserver/controller-manager for working CA root

This is required for a working CA root, as /etc/ssl/certs on a few
Linux distributions just contains a bunch of symlinks.
Container Linux and Debian have symlinks pointing to
/usr/share/ca-certificates, ArchLinux has symlinks pointing
to /etc/ca-certificates.
On Debian /etc/ssl/certs can also include symlinks pointing
to /usr/local/share/ca-certificates for local CA certificates.

Fix: kubeadm/#671

---

**What this PR does / why we need it**:

Without this PR, `controller-manager` and `apiserver` would lack a CA root on some Linux distro (ex: Container Linux) which for example break flexplugins which require a CA root [[1]](https://github.com/kubernetes-incubator/external-storage/issues/571#issuecomment-360155462).

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes https://github.com/kubernetes/kubeadm/issues/671

**Special notes for your reviewer**:

**Release note**:
```release-note
Mount additional paths required for a working CA root, for setups where /etc/ssl/certs doesn't contains certificates but just symlink.
```

/sig sig-kubeadm