Without this setting, bifrost creates a bifrost firewalld zone only
allowing network traffic for Ironic services and assigns the
provisioning network interface to it, potentially causing loss of
connectivity.

Using the public zone is suggested as a workaround [1] but is not
sufficient: it allows SSH traffic, but blocks other services deployed on
the seed, such as Docker registry traffic.

[1] https://review.opendev.org/#/c/754406/

Change-Id: I80f9d95f02e11fda5916f9a9dd257b688a9db7e2
Story: 2008153
Task: 40899