Run openstack command to apply quotas from the undercloud

Without this patch, the openstack commands are executed from the
tester_node, which is not necessarily the undercloud node.

Change-Id: I80ce48f416f474f24fe1a1b12c0883d58d3ac1d0

infrared_plugin/roles/tobiko-ir-before-run/defaults/main.yaml

@@ -1,4 +1,4 @@
 ---
 
 # OpenStack client credentials
-stackrc_file: '{{ ansible_user_dir }}/overcloudrc'
+stackrc_file: '~/overcloudrc'

infrared_plugin/roles/tobiko-ir-before-run/tasks/main.yaml

@@ -5,6 +5,7 @@
     source {{ stackrc_file }}
     openstack quota set --{{ item.key }} {{ item.value }} $OS_PROJECT_NAME
   with_dict: "{{ quota | default({}) }}"
+  delegate_to: "{{ groups.undercloud|first }}"
 
 - name: ensure auto ssh key exchange in test host
   block: