playbooks: roles: Drop explicit 'delegate_to' options

Bifrost instructions suggest to use 'connection: local' when calling any
of the roles. However, there are scenarios which the roles can be
delegated to some other host. The explicit 'delegate_to' statements
prevent us from doing that and they are not necessary if we use
'connection: local' anyway. As such we drop the explicit statements to
make the roles a bit more flexible.

Change-Id: Ifc983992125d203899d74b8bf997f9f58f528978

playbooks/roles/bifrost-deploy-nodes-dynamic/tasks/main.yml

@@ -100,5 +100,4 @@
       root_gb: 10
     wait: "{{ wait_for_node_deploy }}"
     timeout: " {{ wait_timeout | default(1800) }}"
-  delegate_to: localhost
   when: instance_info is not defined or ( instance_info is defined and instance_info | to_json == '{}' )

playbooks/roles/bifrost-unprovision-node-dynamic/tasks/main.yml

@@ -43,4 +43,3 @@
     name: "{{ name | default() }}"
     state: absent
     instance_info: "{}"
-  delegate_to: localhost

playbooks/roles/ironic-delete-dynamic/tasks/main.yml

@@ -45,4 +45,3 @@
     state: absent
     nics: "{{ nics }}"
     driver_info: "{}"
-  delegate_to: localhost