Replacing protobuf-format in SIRI-Updater with standard xml

[lassetyr]

Summary

Replaces the usage of proprietary protobuf-format for SIRI ET-data with standard XML.

Issue

The protobuf-solution was very sensitive to changes, and upgrading protobuf-java (e.g. as in #6342) caused OTP to no longer being able to process SIRI ET-data.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 69.79%. Comparing base (47dece2) to head (f3d4028).
Report is 157 commits behind head on dev-2.x.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...r/google/GooglePubsubEstimatedTimetableSource.java	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             dev-2.x    #6409   +/-   ##
==========================================
  Coverage      69.79%   69.79%           
  Complexity     18089    18089           
==========================================
  Files           2064     2064           
  Lines          77209    77208    -1     
  Branches        7859     7859           
==========================================
  Hits           53886    53886           
  Misses         20566    20566           
+ Partials        2757     2756    -1     

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[leonardehrenfried]

This doesn't touch the core code at all and seems reasonable, so I approve.

I have not tested that it actually works.

[leonardehrenfried]

It seems that the new CI workflow is somehow not triggered since this PR was opened beforehand.

Let me know if you want me to admin-merge this.

[vpaturet]

@leonardehrenfried yes, please merge.