Remove excess data splitter calls

[bchen1116]

Noticed that my previous PR removing the sampling data splitter didn't remove some extra lines that called the data splitter.

Since we are now defaulting to StratifiedKFold and no longer have data splitters with a transform_sample method, I removed the excess code

[codecov]

Codecov Report

Merging #2253 (71d3916) into main (6499428) will increase coverage by 10.4%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            main    #2253      +/-   ##
=========================================
+ Coverage   89.6%   100.0%   +10.4%     
=========================================
  Files        280      280              
  Lines      24330    24322       -8     
=========================================
+ Hits       21780    24300    +2520     
+ Misses      2550       22    -2528     

Impacted Files	Coverage Δ
evalml/automl/automl_search.py	100.0% <ø> (+1.4%)	⬆️
evalml/pipelines/utils.py	100.0% <0.0%> (+1.0%)	⬆️
evalml/tests/conftest.py	100.0% <0.0%> (+1.1%)	⬆️
...derstanding/prediction_explanations/_algorithms.py	98.9% <0.0%> (+1.2%)	⬆️
evalml/tests/component_tests/test_estimators.py	100.0% <0.0%> (+1.9%)	⬆️
evalml/tests/component_tests/test_components.py	100.0% <0.0%> (+2.8%)	⬆️
evalml/tests/utils_tests/test_dependencies.py	88.9% <0.0%> (+3.8%)	⬆️
evalml/tests/component_tests/test_utils.py	97.5% <0.0%> (+3.8%)	⬆️
...valml/tests/pipeline_tests/test_component_graph.py	100.0% <0.0%> (+3.9%)	⬆️
... and 35 more

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[jeremyliweishih]

looks good!

[angela97lin]

Did codecov not catch this, if we don't have anything that calls transform_sample?

[freddyaboulton]

Thanks @bchen1116 !