Install dracut-generic-config package

dracut has a "hostonly" mode where it builds an initramfs that is
suitable for booting the system it is building on.  This is on by
default, but obviously in our nested multi-platform chroot situation
this is fraught with danger.

As highlighted by [1] our builds were inadvertently turning off
"hostonly" mode when the mountpoints in the chroot were not found.
The CentOS 7.3 behaviour change broke this and we ended up with an
initramfs with no file-system modules.

Iaf2a1e8470f642bfaaaad3f9b7f26cfc8cc445c9 introduced a regeneration of
the initramfs, which I think does work as described because it runs in
the loopback device.

However, dracut includes a package that installs configuration
overrides to build a generic initramfs.  This is really what we want,
and should solve the problem no matter where the initramfs is created.

Add this package into yum-minimal and remove the extra re-create call
which should not be necessary.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1405238

Change-Id: I5d203f2abe743cb23a44d449850e692a948e7871

elements/yum-minimal/finalise.d/55-dracut-recreate

@@ -1,12 +0,0 @@
-#!/bin/bash
-
-# Recreate the initramfs within the loop device so everything gets
-# picked up correctly.
-
-if [ ${DIB_DEBUG_TRACE:-1} -gt 0 ]; then
-    set -x
-fi
-set -eu
-set -o pipefail
-
-dracut --regenerate-all --force --verbose

elements/yum-minimal/package-installs.yaml

@@ -1,5 +1,6 @@
 audit:
 dracut:
+dracut-config-generic:
 grubby:
 kernel:
 initscripts: