Swap xinetd/tftp-server for dnsmasq to support ironic-pxe operations

tftp-server and xinetd are not anticipated to be in RHEL9 and as
such we need to remove their use in order to facilitate a transition
to RHEL9 when the time comes.

In this case, we're anticipating we can just directly launch dnsmasq
instead of in.tftpd directly within the container.

Change-Id: Ie75aa0f2994a4cf662905b912231a12e3bd8afe7

deployment/ironic/ironic-pxe-container-puppet.yaml

@@ -122,8 +122,12 @@ outputs:
           ironic_pxe_tftp:
             start_order: 90
             image: &ironic_pxe_image {get_param: ContainerIronicPxeImage}
-            command: ['/bin/bash', '-c', 'BIND_HOST=$(hiera ironic::pxe::tftp_bind_host -c /etc/puppet/hiera.yaml); /usr/sbin/in.tftpd --foreground --user root --address $BIND_HOST:69 --map-file /var/lib/ironic/tftpboot/map-file /var/lib/ironic/tftpboot']
+            command: ['/bin/bash', '-c', 'BIND_HOST=$(hiera ironic::pxe::tftp_bind_host -c /etc/puppet/hiera.yaml); /usr/sbin/dnsmasq --keep-in-foreground --log-facility=/var/log/ironic/dnsmasq.log --user=root --conf-file=/dev/null --listen-address=$BIND_HOST --port=0 --enable-tftp --tftp-root=/var/lib/ironic/tftpboot']
             net: host
+            cap_add:
+              - NET_ADMIN
+              - NET_RAW
+              - SETUID
             privileged: false
             restart: always
             healthcheck:

releasenotes/notes/change-ironic-tftp-service-21cc25629b15992f.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Changes the ironic PXE container TFTP service from ``in.tftpd`` to use
+    the ``dnsmasq`` TFTP service. This is because the ``in.tftpd`` service
+    is not anticipated to be carried by Linux distributions moving forward,
+    and ``dnsmasq`` is actively maintained.