Fix timestops margins

[SharglutDev]

See commits for details

close #8066
close #8067

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 67.01031% with 32 lines in your changes missing coverage. Please review.

Project coverage is 28.05%. Comparing base (67d50c4) to head (bc52bb6).
Report is 1 commits behind head on dev.

Files	Patch %	Lines
...alStudies/hooks/useSetupItineraryForTrainUpdate.ts	0.00%	13 Missing ⚠️
...onents/ManageTrainSchedule/helpers/formatMargin.ts	0.00%	8 Missing ⚠️
front/src/modules/timesStops/TimesStops.tsx	0.00%	6 Missing ⚠️
...ont/src/modules/pathfinding/hook/usePathfinding.ts	0.00%	2 Missing ⚠️
tests/tests/test_stdcm.py	96.49%	2 Missing ⚠️
front/src/applications/stdcm/utils/createMargin.ts	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@             Coverage Diff              @@
##                dev    #8077      +/-   ##
============================================
- Coverage     28.06%   28.05%   -0.02%     
  Complexity     2081     2081              
============================================
  Files          1289     1289              
  Lines        157704   157713       +9     
  Branches       3116     3116              
============================================
- Hits          44265    44246      -19     
- Misses       111564   111592      +28     
  Partials       1875     1875              

Flag	Coverage Δ
core	75.11% <ø> (ø)
editoast	70.74% <100.00%> (-0.05%)	⬇️
front	9.90% <6.25%> (-0.01%)	⬇️
gateway	2.34% <ø> (ø)
railjson_generator	87.49% <ø> (ø)
tests	73.18% <96.49%> (ø)

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[emersion]

Seems like there is a strange side-effect of this PR: when no margin is set, clicking on the margin cell for the origin in the table prefills with "none":

[emersion]

Also, after saving a margin on the origin and re-editing the train, there is a "0%" one showing up on the destination:

[SharglutDev]

Thank you for spotting these. Should be fixed.

[emersion]

LGTM!

editoast throws an error when setting a 0% margin on origin but this is being discussed separately.

[shenriotpro]

LGTM for tests/

[leovalais]

LGTM (editoast; not tested)

[Math-R]

lgtm & tested

[flomonster]

Go 🎉

detect something potentially

[Math-R]

Find a bug unrelated to this PR, lgtm