Updated package dependency for 'Rocky' builds
Updated package dependency for 'Rocky' builds

When installing packages from the openstack rocky repo, they now require
python2-docker which obsoletes python-docker-py. This change is done only for
centos 7.x builds.

Change-Id: I4f4047fff374f12790764fa9ebf4ad4aea8a531b
Partial-Jira-Bug: JCB-218848

Juniper/contrail-packages,Juniper/contrail-packages