perf(graphql): add n+1 test and fix a regression on champ siret

[tchak]

Loaders::Association.for contrairement à Loaders::Record.for n'override pas le travail fait par le DossierPreloader ou un includes

[codecov]

Codecov Report

Attention: Patch coverage is 92.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 84.42%. Comparing base (54b5401) to head (3617aa8).

Files with missing lines	Patch %	Lines
app/graphql/types/champs/carte_champ_type.rb	0.00%	1 Missing ⚠️
app/graphql/types/dossier_type.rb	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11290      +/-   ##
==========================================
- Coverage   84.43%   84.42%   -0.01%     
==========================================
  Files        1211     1210       -1     
  Lines       26688    26667      -21     
  Branches     5038     5033       -5     
==========================================
- Hits        22533    22514      -19     
+ Misses       4155     4153       -2     

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