Revert "Pin registry image to 2019.2.6"

This reverts commit 80646406a0cccd99b65be47b60092881b7df6231.

Reason for revert: not helpful

Change-Id: I0ecf433428a2dc072414bc1e1f427232bba4e15a
diff --git a/docker-registry.yml b/docker-registry.yml
index 0380594..12cdddf 100644
--- a/docker-registry.yml
+++ b/docker-registry.yml
@@ -12,7 +12,7 @@
                 replicas: 1
                 restart_policy:
                   condition: any
-              image: docker-prod-local.docker.mirantis.net/mirantis/external/registry:2019.2.6
+              image: docker-prod-local.docker.mirantis.net/mirantis/external/registry:${_param:mcp_version}
               ports:
                 - 15000:5000
               volumes: