Fix stacked ensembler n_jobs arg for Iterative Algorithm

[bchen1116]

fix #1672

[codecov]

Codecov Report

Merging #1706 (12651da) into main (d96defd) will increase coverage by 0.1%.
The diff coverage is 100.0%.

@@            Coverage Diff            @@
##             main    #1706     +/-   ##
=========================================
+ Coverage   100.0%   100.0%   +0.1%     
=========================================
  Files         242      242             
  Lines       19143    19174     +31     
=========================================
+ Hits        19135    19166     +31     
  Misses          8        8             

Impacted Files	Coverage Δ
...lml/automl/automl_algorithm/iterative_algorithm.py	100.0% <ø> (ø)
evalml/pipelines/utils.py	100.0% <100.0%> (ø)
...lml/tests/automl_tests/test_iterative_algorithm.py	100.0% <100.0%> (ø)

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[chukarsten]

I think the only thing this needs is a doctoring update for _make_stacked_ensemble_pipeline(). Looks good though.

[chukarsten]

Thanks!

[angela97lin]

Looking good, left comments on adding check for ensemble being run and docstr cleanup.

[freddyaboulton]

Thanks for the fix @bchen1116 !

[angela97lin]

Thank you for making the changes! One more docstring comment but looks good :)