Horizon subcloud Host Inventory page does not load during upgrade

[Fabrizio Perez]

Brief Description
------------------
When navigating to subcloud Host Inventory or Software Management page in Horizon, it fails to load with errors.
This happens having a subcloud with Centos and SystemController with Debian.

Severity
------------------
Major: System/Feature is usable but degraded

Steps to Reproduce
------------------
  Upgrade System Controllers to 22.12
  Still have at least one 21.12 subcloud
  Horizon - Drop down at top -> Switch to Subclouds
  Click Alarm & Event Details on the 21.12 subcloud (note that the dropdown at the top should now show "admin - subcloud-name" )
  Select Admin -> Platform -> Host Inventory
  Host Inventory page fails to load with Errors (see screenshot)

Expected Behavior
------------------
Pages with Host Inventory and software management loaded

Actual Behavior
----------------
Horizon is not able to load it.

Reproducibility
---------------
%100

System Configuration
--------------------
DC

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/gui/+/892575
Committed: https://opendev.org/starlingx/gui/commit/99ece544e54b5030581c5ec0939c649fa2c163f6
Submitter: "Zuul (22348)"
Branch: master

commit 99ece544e54b5030581c5ec0939c649fa2c163f6
Author: fperez <email address hidden>
Date: Wed Aug 23 15:28:57 2023 -0300

    Fix for Horizon inventory in subclouds upgrade

    When dealing with a subcloud where Centos and SystemController have
    already been upgraded to Debian, Horizon encounters difficulties
    loading Host Inventory and Software Management pages. This issue
    arises due to variations in host attributes between different
    versions.

    To address this, any expected but missing attributes will be
    assigned default values before loading the page.

    Additionally, adding a fix for issues with sphinx version for this package

    Test Plan:
    - Select the target subcloud with the previous version. Navigate to
      Platform -> Host Inventory and confirm the successful loading of
      the Host table.
    - Select the target subcloud. Navigate to Platform -> Host Inventory
      and confirm the ability to load the Edit Host modal and Host
      details.
    - Select the target subcloud. Navigate to Platform -> Software
      Management and confirm the successful loading of patch details for
      this host.

    closes-bug: 2032838

    Signed-off-by: fperez <email address hidden>
    Change-Id: I671fcca81c14a787d4c55f823d1dae793fe2df35