Clear client error message for system load-import failure due to no diskspace

[Junfeng Li]

Brief Description
-----------------
If the /scratch partition doesn't have enough disk space for running command system load-import, the error message is very generic to ask users to check sysinv.log. We'd like to see more specific error messages which step went wrong during the load import process.

Severity
--------
Minor

Steps to Reproduce
------------------
1. Make the /scratch partition have less than 2GB free disk space.
2. Use system load-import command to load the iso and sig files

Expected Behavior
------------------
Load is imported successfully

Actual Behavior
----------------
Load import failed due to insufficient disk space on /scratch

Reproducibility
---------------
Reproducible

System Configuration
--------------------
All

Workaround
----------
free disk space on /scratch and re-run system load-import command

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/config/+/847408

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/config/+/847408
Committed: https://opendev.org/starlingx/config/commit/8175c0069eac64ff1370e63a8bed1ce84f2c457f
Submitter: "Zuul (22348)"
Branch: master

commit 8175c0069eac64ff1370e63a8bed1ce84f2c457f
Author: Junfeng (Shawn) Li <email address hidden>
Date: Thu Jun 23 16:44:22 2022 -0400

    Populate more specific load import error messages

    Raise each exception from_upload_file() method and populate
    it to client side error messages. This change doesn't add or remove any
    new behavior. It only update the error message format in the log.

    Closes-Bug: 1979689

    Test Plan:
    PASS: Patch local duplex system and trigger one exception from _upload_file()
          method to verify the error message is populated
    PASS: Run 'system load-import bootimage.iso bootimage.sig' successfully and
          verify in 'system load-list' with sufficient /scratch diskspace

    Signed-off-by: Junfeng (Shawn) Li <email address hidden>
    Change-Id: I4cbf0ce3f0f9036e41d65d7c19a84d92f768ae32