Changed the default path for the offline iperf packages

The default path to the offline iperf3 package and its dependencies
is set to /opt/packages now due to the new approach with the offline
toolset image where these packages are already present.

With new iperf3 version at /opt/packages, we need more dependencies,
so the search for the offline packages is changed.

Change-Id: If2dbe537a25905ec7260a5133e1956f60ae2c73e
diff --git a/global_config.yaml b/global_config.yaml
index b297350..f6213ca 100644
--- a/global_config.yaml
+++ b/global_config.yaml
@@ -13,7 +13,7 @@
 external_network: 'public'
 iperf_prep_string: "sudo /bin/bash -c 'echo \"91.189.88.161        archive.ubuntu.com\" >> /etc/hosts'"
 internet_at_vms: 'true' # whether Internet is present at OpenStack VMs and iperf can be installed with apt
-iperf_deb_package_dir_path: '/artifacts/mos-spt/'
+iperf_deb_package_dir_path: '/opt/packages/'
 iperf_time: 60 # time in seconds to transmit for (iperf -t option)
 ssh_timeout: 500
 skipped_nodes: []