labs: fix reading tenant id

Currently, setup_neutron_controller is reading the string "id" rather
than the actual tenant id which is in $4 (the pipes used as separators
in the table count as fields, too).

While we're at it, replace "service" with "$SERVICE_TENANT_NAME".

Change-Id: Id47d5c10ce426ff42237105c02f0dffdf4632cfc