Fix ensemble partial dependence bug

[angela97lin]

Closes #2712

[codecov]

Codecov Report

Merging #2714 (de192a8) into main (6607edf) will decrease coverage by 0.8%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main   #2714     +/-   ##
=======================================
- Coverage   99.9%   99.2%   -0.7%     
=======================================
  Files        301     301             
  Lines      27678   27688     +10     
=======================================
- Hits       27634   27442    -192     
- Misses        44     246    +202     

Impacted Files	Coverage Δ
evalml/pipelines/components/utils.py	100.0% <100.0%> (ø)
...del_understanding_tests/test_partial_dependence.py	99.3% <100.0%> (-0.7%)	⬇️
...l/tests/automl_tests/test_pipeline_search_plots.py	25.6% <0.0%> (-74.4%)	⬇️
evalml/automl/pipeline_search_plots.py	46.5% <0.0%> (-53.5%)	⬇️
...ests/automl_tests/test_automl_search_regression.py	84.6% <0.0%> (-15.4%)	⬇️
.../automl_tests/test_automl_search_classification.py	89.5% <0.0%> (-10.5%)	⬇️
evalml/tests/automl_tests/test_automl_utils.py	90.7% <0.0%> (-9.3%)	⬇️
...lml/tests/automl_tests/test_iterative_algorithm.py	95.6% <0.0%> (-4.4%)	⬇️
evalml/automl/utils.py	98.4% <0.0%> (-1.6%)	⬇️
... and 1 more

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[angela97lin]

Not used so deleting :0

[chukarsten]

Awesome! Great detective work!