Fix the docker build image workflow

Fix the docker build image workflow

Fixed the Docker build image workflow.

Added seperate tagging for SNAPSHOT-latest and STAGING-latest

There are two docker jobs currently. One produces SNAPSHOT images
and other produces STAGING images. SNAPSHOT images are build from
nexus2 maven snapshots artifacts where as STAGING images are built
from nexus2 maven releases artifacts.

Removed libxml2-utils dependency from docker build image script.
Since the dedicated docker node might be shared by multiple jobs,
apt-get install inside the script might cause conflict and cause
failure of the docker jenkins jobs. Moved the dependency to be part
of the jenkins infrastructure node itself.

Change-Id: I122974c984b1b0ece98bbd5a783d7923504abf3e
Issue-ID: OPTFRA-301
Signed-off-by: Dileep Ranganathan <dileep.ranganathan@intel.com>