Fix legacy pytest fixtures

[danielhollas]

Fixes #6881

Error in the failing tests:

Error: Invalid value for '-p' / '--profile': profile c01e3952-46ee-4a12-9fe8-a960a5593e19 does not exist

[codecov]

Codecov Report

Attention: Patch coverage is 98.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.20%. Comparing base (43176cb) to head (e5adde7).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aiida/manage/tests/test_pytest_fixtures.py	98.25%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6882      +/-   ##
==========================================
+ Coverage   78.60%   79.20%   +0.60%     
==========================================
  Files         567      568       +1     
  Lines       43097    43183      +86     
==========================================
+ Hits        33871    34197     +326     
+ Misses       9226     8986     -240     

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[danielhollas]

@agoscinski just heads up that I think this should be included in the 2.7.0 release otherwise we risk breaking people's CIs (as it broke aiidalab-widgets-base). I can work on this over the weekend to drive it home.