enh: Operator auth. Better http error

[olethanh]

make it more clear what the error is so it is easier for client and sdk developper to debug auth problem

Explain what problem this PR is resolving

Related ClickUp, GitHub or Jira tickets : ALEPH-XXX

Self proofreading checklist

• The new code clear, easy to read and well commented.
• New code does not duplicate the functions of builtin or popular libraries.
• An LLM was used to review the new code and look for simplifications.
• New classes and functions contain docstrings explaining what they provide.
• All new code is covered by relevant tests.
• Documentation has been updated regarding these changes.
• Dependencies update in the project.toml have been mirrored in the Debian package build script packaging/Makefile

Changes

Explain the changes that were made. The idea is not to list exhaustively all the changes made (GitHub already provides a full diff), but to help the reviewers better understand:

• which specific file changes go together, e.g: when creating a table in the front-end, there usually is a config file that goes with it
• the reasoning behind some changes, e.g: deleted files because they are now redundant
• the behaviour to expect, e.g: tooltip has purple background color because the client likes it so, changed a key in the API response to be consistent with other endpoints

How to test

Explain how to test your PR.
If a specific config is required explain it here (account, data entry, ...)

Print screen / video

Upload here screenshots or videos showing the changes if relevant.

Notes

Things that the reviewers should know: known bugs that are out of the scope of the PR, other trade-offs that were made.
If the PR depends on a PR in another repo, or merges into another PR (i.o. main), it should also be mentioned here

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 64.54%. Comparing base (e5d6d3b) to head (cee5a11).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aleph/vm/orchestrator/views/authentication.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #788   +/-   ##
=======================================
  Coverage   64.54%   64.54%           
=======================================
  Files          78       78           
  Lines        7087     7087           
  Branches      597      597           
=======================================
  Hits         4574     4574           
  Misses       2312     2312           
  Partials      201      201           

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