Update to OTLP 1.1, regenerate protos and pdata

[jmacd]

Description: Updates to OTLP 1.1, published in January 2024. Updates the otel/build-protobuf Docker image to the current release label.

User-visible protocol changes: Adds Span flags and SpanLink flags.

Link to tracking Issue:
Fixes #9587
Fixes #9550

Testing: make test

Documentation: Could not find any documentation on this process, added some in CONTRIBUTING.md.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (939c740) 90.62% compared to head (284a065) 90.61%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9588      +/-   ##
==========================================
- Coverage   90.62%   90.61%   -0.02%     
==========================================
  Files         347      347              
  Lines       18238    18250      +12     
==========================================
+ Hits        16528    16537       +9     
- Misses       1381     1383       +2     
- Partials      329      330       +1     

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[codeboten]

Thanks for adding the documentation for the process 👍🏻

[bogdandrutu]

Thanks for this. In the future I would prefer to have separate PRs for bumping protos vs adding the new fields (easier to review).