[ci] ci environments from tripleo-heat-templates pointing to /usr/share/openstack-tripleo-heat-templates

When trying to run the upgrade steps with the current master tripleo-heat-templates content, the upgrade failed with:

2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare env_base_url)
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare File "/usr/lib/python2.7/site-packages/heatclient/common/template_utils.py", line 357, in resolve_environment_urls
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare is_object=is_object, object_request=object_request)
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare File "/usr/lib/python2.7/site-packages/heatclient/common/template_utils.py", line 161, in get_file_contents
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare file_content = utils.read_url_content(str_url)
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare File "/usr/lib/python2.7/site-packages/heatclient/common/utils.py", line 417, in read_url_content
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare raise exc.CommandError(_('Could not fetch contents for %s') % url)
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare CommandError: Could not fetch contents for file:///usr/share/openstack-tripleo-heat-templates/network/ports/storage.yaml
2019-03-06 14:25:54.445 322783 ERROR tripleoclient.v1.overcloud_upgrade.MajorUpgradePrepare
2019-03-06 14:25:54.448 322783 ERROR openstack [-] Could not fetch contents for file:///usr/share/openstack-tripleo-heat-templates/network/ports/storage.yaml: CommandError: Could not fetch contents for file:///usr/share/openstack-tripleo-heat-templates/network/ports/storage.yaml
2019-03-06 14:25:54.453 322783 INFO osc_lib.shell [-] END return value: 1
+ status_code=1
+ openstack stack list
+ grep -q overcloud
+ openstack stack list
+ grep -Eq '(CREATE|UPDATE)_COMPLETE'
+ openstack overcloud status
+ grep -Eq DEPLOY_SUCCESS
+ exit 1

The overcloud upgrade prepare command is as follows:

openstack overcloud upgrade prepare --override-ansible-cfg /home/zuul/custom_ansible.cfg --templates /home/zuul/tripleo-heat-templates --libvirt-type qemu --timeout 168 --ntp-server pool.ntp.org -e /home/zuul/cloud-names.yaml -e /home/zuul/tripleo-heat-templates/environments/docker-ha.yaml -e /home/zuul/containers-prepare-parameter.yaml -e /home/zuul/tripleo-heat-templates/environments/docker.yaml -e /home/zuul/tripleo-heat-templates/ci/environments/network/multiple-nics/network-isolation-absolute.yaml -e /home/zuul/tripleo-heat-templates/ci/environments/network/multiple-nics/network-environment.yaml -e /home/zuul/overcloud_network_params.yaml -e /home/zuul/tripleo-heat-templates/environments/low-memory-usage.yaml -e /opt/stack/new/tripleo-ci/test-environments/worker-config.yaml -e /home/zuul/tripleo-heat-templates/environments/debug.yaml -e /home/zuul/enable-tls.yaml -e /home/zuul/tripleo-heat-templates/environments/ssl/tls-endpoints-public-ip.yaml -e /home/zuul/inject-trust-anchor.yaml -e /home/zuul/tripleo-heat-templates/environments/disable-telemetry.yaml --validation-warnings-fatal --compute-scale 1 --control-scale 3 -e /home/zuul/tripleo-heat-templates/ci/environments/ovb-ha.yaml

Where the --templates location points into ~/tripleo-heat-templates/ directory.

The source of the problem seems to be with the /home/zuul/tripleo-heat-templates/ci/environments/network/multiple-nics/network-isolation-absolute.yaml environment file, which has parameters pointing into /usr/share/openstack-tripleo-heat-templates. These paths need to be relative instead.