Comment 2 for bug 1803312

Reviewed: https://review.openstack.org/617914
Committed: https://git.openstack.org/cgit/openstack-dev/grenade/commit/?id=8afd7beb079dc4d9bf5e4e69c13a8c8a8bd060d3
Submitter: Zuul
Branch: master

commit 8afd7beb079dc4d9bf5e4e69c13a8c8a8bd060d3
Author: Matt Riedemann <email address hidden>
Date: Wed Nov 14 04:07:59 2018 -0500

    Use openstack resource provider inventory show to get inventory

    Under python3, the output of the openstack resource provider
    inventory list command is random which breaks how the
    _get_inventory_value function is used to store and verify
    inventory before and after the upgrade.

    This change uses the "openstack resource provider inventory show"
    command to target the specific resource class and column value (total)
    so we don't have to worry about sort order.

    While in here, a comment is left about why we can't do the
    same for getting the resource class allocation value.

    Change-Id: I1e8dadae631bee87628c5b5390609deb8a1a71e5
    Closes-Bug: #1803312