[release-2.40.0] Fix FlatMap numpy array bug

[TheNeuralBit]

Cherry-pick #22006 into release branch.

This change fixes a regression introduced in 0de9821, which breaks pipelines that return a numpy array (or any other iterable that has overridden __bool__ to raise an error) in a FlatMap.

GitHub Actions Tests Status (on master branch)

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[TheNeuralBit]

R: @pabloem

[TheNeuralBit]

Run Python_PVR_Flink PreCommit

[codecov]

Codecov Report

Merging #22007 (92a57ce) into release-2.40.0 (882b608) will increase coverage by 0.00%.
The diff coverage is 75.00%.

@@               Coverage Diff               @@
##           release-2.40.0   #22007   +/-   ##
===============================================
  Coverage           73.97%   73.97%           
===============================================
  Files                 702      702           
  Lines               92833    92835    +2     
===============================================
+ Hits                68670    68679    +9     
+ Misses              22908    22901    -7     
  Partials             1255     1255           

Flag	Coverage Δ
python	83.58% <75.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
sdks/python/apache_beam/runners/common.py	88.59% <75.00%> (-0.10%)	⬇️
...ks/python/apache_beam/runners/worker/sdk_worker.py	89.09% <0.00%> (+0.15%)	⬆️
...hon/apache_beam/runners/worker/bundle_processor.py	93.67% <0.00%> (+0.24%)	⬆️
...che_beam/runners/interactive/interactive_runner.py	91.39% <0.00%> (+1.32%)	⬆️
sdks/python/apache_beam/utils/interactive_utils.py	97.56% <0.00%> (+2.43%)	⬆️
.../python/apache_beam/testing/test_stream_service.py	92.85% <0.00%> (+4.76%)	⬆️

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[pabloem]

LGTM!