front: fix wrong suggeredvias selection

[SharglutDev]

close #6120

• format the suggeredVias without the duplicates
• add some margin for the icons to prevent overflow with the scrollbar
• some refacto for non usefull code

⚠️ This fixes only the related issue. The component is still weird because of this bug

[codecov]

Codecov Report

Attention: 14 lines in your changes are missing coverage. Please review.

Comparison is base (3a3bc3f) 26.93% compared to head (e0e04c6) 26.93%.

Files	Patch %	Lines
...anageTrainSchedule/Itinerary/ModalSuggeredVias.tsx	0.00%	13 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                dev    #6125      +/-   ##
============================================
- Coverage     26.93%   26.93%   -0.01%     
  Complexity     2136     2136              
============================================
  Files           961      961              
  Lines        124258   124259       +1     
  Branches       2574     2574              
============================================
  Hits          33472    33472              
- Misses        89297    89298       +1     
  Partials       1489     1489              

Flag	Coverage Δ
core	78.88% <ø> (ø)
editoast	75.46% <ø> (ø)
front	8.69% <0.00%> (-0.01%)	⬇️
gateway	2.54% <ø> (ø)
tests	81.77% <ø> (ø)

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[clarani]

LGTM, tested ✅