Disable tempest jobs for doc only changes
Disable tempest jobs for doc only changes

For doc only changes, there is no need to run tempest jobs which
require more time. This commit disables the tempest jobs if
doc only changes,
only unit-test changes

Closes-Bug:#1732829
Change-Id: Idc0604beff383f435705acfd55de57258a71332c

openstack/congress,openstack/congress