[adoption_osp_deploy] Remove dot typo

This commit removes a typo (unnecessary dot) added by #3397 .

Signed-off-by: Luca Miccini <lmiccini@redhat.com>

Author: lmiccini

roles/adoption_osp_deploy/tasks/prepare_overcloud.yml

@@ -256,7 +256,7 @@
         _node_net: "{{ cifmw_networking_env_definition.instances[overcloud_vm] }}"
         _ctlplane_node_net: "{{ _node_net.networks.ctlplane | default({}) }}"
         _ctlplane_net: "{{ cifmw_networking_env_definition.networks.ctlplane | default({}) }}"
-        _dns_server: "{{ _ctlplane_net.[dns_version|default('dns_v4')] | default(None) }}"
+        _dns_server: "{{ _ctlplane_net[dns_version|default('dns_v4')] | default(None) }}"
         _os_net_config_template: "{{ 'os_net_config_overcloud_bgp.yml.j2' if (cifmw_adoption_osp_deploy_bgp | bool) else 'os_net_config_overcloud.yml.j2' }}"
         # Non-BGP specific vars (may not exist in BGP mode, so use default)
         _ctlplane_ip: "{{ _ctlplane_node_net[ip_version|default('ip_v4')] | default(None) }}"