Correct the test for proxy.http

proxy.http | trim returns "None" instead of "". To test if proxy should
be used, when: proxy.http should be good enough.
We don't have to test if proxy.http is defined or not. Because it is
alredy defined in defaults/main.yaml.

Change-Id: Ia6330907d22c3f46586aec16db3eefab1a5bbac9
Task: 28755
Story: 2004717

roles/build-images/tasks/kubeadm-aio.yaml

@@ -41,7 +41,7 @@
     #        HELM_VERSION: "{{ version.helm }}"
     #        CHARTS: "calico,flannel,tiller,kube-dns"
     - name: Kubeadm-AIO image build path with proxy
-      when: proxy.http is defined and (proxy.http | trim != "")
+      when: proxy.http
       shell: |-
               set -e
               docker build \
@@ -70,7 +70,7 @@
         chdir: "{{ kubeadm_aio_path.stdout }}/"
         executable: /bin/bash
     - name: Kubeadm-AIO image build path
-      when: proxy.http is undefined or (proxy.http | trim == "")
+      when: not proxy.http
       shell: |-
               set -e
               docker build \

roles/deploy-docker/tasks/main.yaml

@@ -40,13 +40,13 @@
 
 # NOTE: (lamt) Setting up the proxy before installing docker
 - name: ensure docker.service.d directory exists
-  when: proxy.http is defined and (proxy.http | trim != "")
+  when: proxy.http
   file:
     path: /etc/systemd/system/docker.service.d
     state: directory
 
 - name: proxy | moving proxy systemd unit into place
-  when: proxy.http is defined and (proxy.http | trim != "")
+  when: proxy.http
   template:
     src: http-proxy.conf.j2
     dest: /etc/systemd/system/docker.service.d/http-proxy.conf