Remove dhcp-sequential-ip in ironic dnsmasq config

With this option enabled, dnsmasq can offer the same IP address to
multiple hosts when their requests are close to each other. Remove this
option in order to use the built-in hashing mechanism which will
allocate random IP addresses, which should be less likely to conflict.

Closes-Bug: #1991390
Change-Id: I09a9fa2d0c54635b899ad7906cc2e2e4580ef5ad

ansible/roles/ironic/templates/ironic-dnsmasq.conf.j2

@@ -13,7 +13,6 @@ dhcp-range=set:{{ tag }},{{ item.range }},{{ lease_time }}
 dhcp-option=tag:{{ tag }},option:router,{{ item.routers }}
 {% endif %}
 {% endfor %}
-dhcp-sequential-ip
 
 {% if api_address_family == 'ipv6' %}
 {# TODO(yoctozepto): IPv6-only support - DHCPv6 PXE support #}

releasenotes/notes/ironic-dnsmasq-no-dhcp-sequential-ip-13256d6a55e9027f.yaml

+---
+fixes:
+  - |
+    Removes the ``dhcp-sequential-ip`` configuration option from
+    ``ironic_dnsmasq`` to avoid a race condition offering the same IP address
+    to multiple hosts being inspected at the same time.