fix osc gate: post_test_hook.sh not found
fix osc gate: post_test_hook.sh not found

commit I49d54f009021d65c1ae49faf6b3f0a7acdadd7b3 incorrectly
referenced the new location.

the gate is currently broken with the error:
:post_test_hook:L0:   bash -xe /opt/stack/new/python-openstackclient/tests/functional/post_test_hook.sh
bash: /opt/stack/new/python-openstackclient/tests/functional/post_test_hook.sh: No such file or directory

for the actual location [1]

[1] https://github.com/openstack/python-openstackclient/blob/master/openstackclient/tests/functional/post_test_hook.sh

Change-Id: I3efe71c76409af95a6f48259e4a6dd34857e2ef0

Tesora/tesora-project-config,Tesora/tesora-project-config,openstack-infra/project-config,openstack-infra/project-config