fix(stream): reads should emit the dataset number for each dataset

[wellwelwel]

This PR is a debug/fix of #2496, preserving all its commits.

Testing locally:

seq 1000 | xargs -I {} sh -c 'FILTER=test-multi-result-streaming npm run test || echo "Failure at iteration {}" >> failures.log'

• I ran all the CI 3 times, just to make sure.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.32%. Comparing base (9edfd72) to head (f98476d).
Report is 28 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2628   +/-   ##
=======================================
  Coverage   90.32%   90.32%           
=======================================
  Files          71       71           
  Lines       15727    15727           
  Branches     1339     1339           
=======================================
  Hits        14206    14206           
  Misses       1521     1521           

Flag	Coverage Δ
compression-0	90.32% <100.00%> (ø)
compression-1	90.32% <100.00%> (ø)
tls-0	89.85% <100.00%> (ø)
tls-1	90.15% <100.00%> (ø)

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