Revert "revert changes to root-builder"

This reverts commit a740009.

The problem seems to be that we don't have access to the network when
are running libguest tools. For example:
> #11 351.4 time="2024-07-26T13:04:42Z" level=warning msg="stderr> ntpdig: lookup of pool.ntp.org failed, errno -3 = Temporary failure in name resolution\n"

I can reproduce this locally. The problem seems to be that passt, which
is used for networking, cannot create a user namespace inside docker.

libguestfs: command: run: passt
libguestfs: command: run: \ --one-off
libguestfs: command: run: \ --socket /tmp/libguestfsPYvwlq/passt.sock
libguestfs: command: run: \ --pid /tmp/libguestfsPYvwlq/passt1.pid
libguestfs: command: run: \ --address 169.254.2.15
libguestfs: command: run: \ --netmask 16
libguestfs: command: run: \ --mac-addr 52:56:00:00:00:02
libguestfs: command: run: \ --gateway 169.254.2.2
Failed to send 47 bytes to syslog
Don't run as root. Changing to nobody...
Failed to send 55 bytes to syslog
No routable interface for IPv6: IPv6 is disabled
Failed to send 62 bytes to syslog
Couldn't create user namespace: Operation not permitted

The previous patch, however, AFAIU configures buildkit to run on the
host. Let's see if it works...

dockerfiles/root-builder

@@ -1,9 +1,7 @@
 # vim: set ft=dockerfile:
-# Update to latest version: 2024-01-30
-# Note: can be updated to a tag after a version >v0.0.17 is released
-FROM quay.io/lvh-images/lvh@sha256:9effc5161cfb265641f0be36cd9c2e8b9c477fa04ac67c01c1fadfae05269417 AS lvh
+FROM quay.io/lvh-images/lvh:v0.0.19 AS lvh
 
-# rebuild: 20240130.185336
+# rebuild: 20240726.114310
 
 FROM ubuntu:rolling