Use locale param from plan queries for all translations in the GTFS API if accept-language header is not set

[optionsome]

Summary

Updates data fetchers to use the GraphQL utils for determining the locale for translations so that the locale param in plan queries is respected if no accept-language header is used.

Issue

No issue

Unit tests

Not sure if needed

Documentation

No

Changelog

From title

[optionsome]

Idk if we should prefer locale param if one is set over the accept-language header. I have a feeling this logic might have been changed at some point perhaps by myself.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 70.25%. Comparing base (698df74) to head (89c5a3e).
Report is 71 commits behind head on dev-2.x.

Files with missing lines	Patch %	Lines
...anner/apis/gtfs/datafetchers/RoutingErrorImpl.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             dev-2.x    #6546   +/-   ##
==========================================
  Coverage      70.24%   70.25%           
- Complexity     18369    18387   +18     
==========================================
  Files           2087     2088    +1     
  Lines          77381    77425   +44     
  Branches        7839     7843    +4     
==========================================
+ Hits           54358    54395   +37     
- Misses         20249    20258    +9     
+ Partials        2774     2772    -2     

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