Remove GTFS "remove repeated stops" feature

[leonardehrenfried]

Summary

It removes the feature to remove repeated stops from the GTFS processing.

Background

In GTFS Flex feeds it is often required that you have two consecutive stop times with the same stop location but this feature removes one of them, leading to strange API results. (The flex code itself had already ignored the repetition).

I at first wanted to add a special case for flex but then thought that we probably never want to "fix" input data. A quick chat with @optionsome confirms this. For that reason I'm removing the feature altogether.

Note: NeTEx already disables this feature permanently.

Issue

None.

Unit tests

n/a

Documentation

Removed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.07%. Comparing base (1c8fdcb) to head (cbedeab).
⚠️ Report is 112 commits behind head on dev-2.x.

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #6846      +/-   ##
=============================================
+ Coverage      72.00%   72.07%   +0.06%     
- Complexity     19430    19507      +77     
=============================================
  Files           2099     2105       +6     
  Lines          78730    78936     +206     
  Branches        7961     8000      +39     
=============================================
+ Hits           56692    56890     +198     
+ Misses         19233    19230       -3     
- Partials        2805     2816      +11     

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[jessicaKoehnke]

just one small thing, otherwise good!