Don't use opendev docker proxy

Look like using docker proxy is slower and less stable than pulling from
dockerhub directly and contributes to some part of unstable builds.

This reverts commit e3f14aaff3.

Change-Id: I9735ad35ce9240f610479a56eaa38715defa2e04
Signed-off-by: Andrii Ostapenko <andrii.ostapenko@att.com>

playbooks/osh-infra-gate-runner.yaml

@@ -20,9 +20,6 @@
       include_role:
         name: override-images
       when: buildset_registry is defined
-    - name: Use docker mirror
-      include_role:
-        name: use-docker-mirror
     - name: "creating directory for run artifacts"
       file:
         path: "/tmp/artifacts"