[MAINT] use tmp_path in scd lvl tests

[Remi-Gau]

• relates to improve handling of temporary files during testing #3726
• extracted from [WIP] rely more on tmp_path in testing Do Not REVIEW  #3891
• blocked by [MAINT] add file path param to write fake fmri data #3892

[github-actions]

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[codecov]

Codecov Report

Merging #3896 (33d59a6) into main (d4fec68) will decrease coverage by 0.02%.
Report is 7 commits behind head on main.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3896      +/-   ##
==========================================
- Coverage   91.60%   91.59%   -0.02%     
==========================================
  Files         134      134              
  Lines       15751    15753       +2     
  Branches     3281     3281              
==========================================
  Hits        14429    14429              
- Misses        772      773       +1     
- Partials      550      551       +1     

Flag	Coverage Δ
macos-latest_3.10	91.51% <ø> (-0.02%)	⬇️
macos-latest_3.11	91.51% <ø> (-0.02%)	⬇️
macos-latest_3.8	91.48% <ø> (-0.02%)	⬇️
macos-latest_3.9	91.48% <ø> (-0.02%)	⬇️
ubuntu-latest_3.10	91.51% <ø> (-0.02%)	⬇️
ubuntu-latest_3.11	91.51% <ø> (-0.02%)	⬇️
ubuntu-latest_3.8	91.48% <ø> (-0.02%)	⬇️
ubuntu-latest_3.9	91.48% <ø> (-0.02%)	⬇️
windows-latest_3.10	91.46% <ø> (-0.02%)	⬇️
windows-latest_3.11	91.46% <ø> (-0.02%)	⬇️
windows-latest_3.8	91.42% <ø> (-0.02%)	⬇️
windows-latest_3.9	91.42% <ø> (-0.02%)	⬇️

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[ymzayek]

LGTM!