Description of problem:
I'm unable to use the podman_registries_conf variable to set the unqualified-search-registries setting.

Version-Release number of selected component (if applicable):
Automation Hub release of RHEL system roles: redhat.rhel_system_roles-1.21.1

How reproducible:
Every time

Steps to Reproduce:
Configure the podman_registries_conf variable and run the podman role:

    podman_registries_conf:
      unqualified-search-registries: ["registry.access.redhat.com"]

Actual results:
The role fails when run:

TASK [redhat.rhel_system_roles.podman : Update registries config file] **************************************************************************************
An exception occurred during task execution. To see the full traceback, use -vvv. The error was: ansible.errors.AnsibleUndefinedVariable: 'list object' has no attribute 'registry.access.redhat.com'
fatal: [rhel9-server1.example.com]: FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'list object' has no attribute 'registry.access.redhat.com'"}

Expected results:
I would expect this to create the /etc/containers/registries.conf.d/50-systemroles.conf with the following:

unqualified-search-registries = ["registry.access.redhat.com"] 

Additional info:
It appears that the role only supports configuring podman_registries_conf options that are under a namespace such as:

[namespace]
option = value

However, the unqualified-search-registries setting is a global setting that isn't under a namespace. For more info, see "man containers-registries.conf"