fix: show error message from backend API for workspace deletion

[keita-determined]

Description

https://hpe-aiatscale.slack.com/archives/CLCE8D998/p1707939243269789

Test Plan

• Create a workspace with at least one registered model
• Delete the workpspace and check if the toast shows error message from backend API

Commentary (optional)

Checklist

• Changes have been manually QA'd
• User-facing API changes need the "User-facing API Change" label.
• Release notes should be added as a separate file under docs/release-notes/.
  See Release Note for details.
• Licenses should be included for new code which was copied and/or modified from any external code.

Ticket

[netlify]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ba03375) 47.58% compared to head (018fd9f) 42.67%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8848      +/-   ##
==========================================
- Coverage   47.58%   42.67%   -4.91%     
==========================================
  Files        1068      751     -317     
  Lines      170265   131414   -38851     
  Branches     2240     2240              
==========================================
- Hits        81016    56086   -24930     
+ Misses      89091    75170   -13921     
  Partials      158      158              

Flag	Coverage Δ
harness	?
web	42.54% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...ebui/react/src/components/WorkspaceDeleteModal.tsx	0.00% <ø> (ø)

... and 317 files with indirect coverage changes