test: can't launch NSC test assert 404 instead of 403

[NicholasBlaskey]

Ticket

Description

Fix failing test after this
#9140

Notebooks, tensorboards, shells and commands should return 404 trying to launch a workspace you don't have access to.

Test Plan

test passes

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.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.24%. Comparing base (2ced9b9) to head (cf861a9).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9197      +/-   ##
==========================================
- Coverage   45.89%   36.24%   -9.65%     
==========================================
  Files         777      602     -175     
  Lines      107072    94206   -12866     
  Branches     2439     2438       -1     
==========================================
- Hits        49140    34148   -14992     
- Misses      57700    59826    +2126     
  Partials      232      232              

Flag	Coverage Δ
harness	38.56% <ø> (-25.46%)	⬇️
web	35.38% <ø> (ø)

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see 273 files with indirect coverage changes