Attempt to reduce partition size does not return proper error in Horizon

[Fabrizio Perez]

Brief Description
-----------------
Attempt to reduce partition size does not return proper error in Horizon
(Just indicates Danger: There was an error submitting the form. Please try again.)

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

Steps to Reproduce
------------------
Create a new partition from Horizon
Attempt to reduce the size of the partition from horizon Storage tab

Expected Behavior
------------------
Correct error reason returned
eg. Requested partition size must be larger than current size: 15 GiB <= 22.0 GiB

Actual Behavior
----------------
Attempt to reduce partition size does not return proper error in Horizon   Danger error msg returned

horizon .log reports 2023-02-15 20:57:09,022 [INFO] starlingx_dashboard.dashboards.admin.inventory.storages.forms: Failed to update partition.
2023-02-15 20:57:09,022 [ERROR] starlingx_dashboard.dashboards.admin.inventory.storages.forms: Requested partition size must be larger than current size: 15 GiB <= 22.0 GiB

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

System Configuration
--------------------
2023-02-09-18-18-02
simplex HPE blade 11

Branch/Pull Time/Commit
-----------------------
On running system use cat /etc/build.info and grep BUILD_ID
Branch and the time when code was pulled or git commit or cengn load info

Last Pass
---------

Timestamp/Logs
--------------
horizon .log reports 2023-02-15 20:57:09,022 [INFO] starlingx_dashboard.dashboards.admin.inventory.storages.forms: Failed to update partition.
2023-02-15 20:57:09,022 [ERROR] starlingx_dashboard.dashboards.admin.inventory.storages.forms: Requested partition size must be larger than current size: 15 GiB <= 22.0 GiB

Test Activity
-------------
Feature Testing, Regression Testing

Workaround
----------
Do this process using CLI

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/gui/+/880069
Committed: https://opendev.org/starlingx/gui/commit/db9bb2cf03ba1cff7ed7b0b4739d0383b59d17de
Submitter: "Zuul (22348)"
Branch: master

commit db9bb2cf03ba1cff7ed7b0b4739d0383b59d17de
Author: fperez <email address hidden>
Date: Tue Apr 11 13:33:38 2023 -0300

    Fix improper error message when reducing partition size

    When attempting to reduce partition size from the GUI, a generic
    error message is returned. This occurs because providing the complete
    error details to the error handler can lead to the generation of
    a distinct exception.

    Test plan:
      Install Standard. Create partition and
      attempt to reduce size from GUI.
      Verify that error message indicates
      that is not possible to reduce partitions.
      Also verify that right error message is present in
      horizon.log and that any other exception dissapear
      for this action.

    Closes-Bug: 2015918

    Signed-off-by: fperez <email address hidden>
    Change-Id: I9ad7315f9e428d029b30ea230c343a4fe1df8a5f