nix/keys: Fix eval if storeKeysOnMachine is true.

This currently only fixes evaluation but actually doesn't apply the
correct permissions on the key files because they're just links to world
readable files in the Nix store.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
nix/keys: Fix description of storeKeysOnMachine.

As storeKeysOnMachine no longer is true by default (7ae4b27), we
shouldn't say so in the description. Especially because the default
value is already shown in the generated manual along with the
description.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Fix VM tests for hetzner and none backends.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
(cherry picked from commit 66aeeb201446a94f7ebb59461b5efcbc02019a9d)
tests: Add Archive::Cpio to all the coordinators.

This is needed in order to build the initrd for the target machines and
we don't have access to external network resources within the VM test.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
(cherry picked from commit 1bd7182bc1609d602e6193ee4665a6dce45aded4)
tests: Disable packet filtering on all VM tests.

This is only a source for more errors, confusion, more complexity and we
really don't want to test the packet filter here, because we already
have tests in NixOS directly.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
(cherry picked from commit 8feb9223bc5d43517bf4acd93b89a84802d90d05)