Cleanup context from fanout API

[RustedBones]

Part of #4459

[codecov]

Codecov Report

Merging #4873 (4c08ee5) into main (1f32fd6) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 4c08ee5 differs from pull request most recent head 14e04de. Consider uploading reports for the commit 14e04de to get more accurate results

@@            Coverage Diff             @@
##             main    #4873      +/-   ##
==========================================
- Coverage   62.89%   62.89%   -0.01%     
==========================================
  Files         282      282              
  Lines       10574    10575       +1     
  Branches      773      781       +8     
==========================================
  Hits         6651     6651              
- Misses       3923     3924       +1     

Impacted Files	Coverage Δ
...spotify/scio/values/PairSCollectionFunctions.scala	98.22% <100.00%> (ø)
...tify/scio/values/SCollectionWithHotKeyFanout.scala	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes