chore: change udf vec2array to pyspark.ml.functions.vector_to_array

[memoryz]

What changes are proposed in this pull request?

vector_to_array was introduced in Spark 3.0 which replaces the need for udf vec2array.

How is this patch tested?

• Through notebook test automation
• I have written tests (not required for typo or doc fix) and confirmed the proposed feature/bug-fix/change works.

Does this PR change any dependencies?

• No. You can skip this section.
• Yes. Make sure the dependencies are resolved correctly, and list changes here.

Does this PR add a new feature? If so, have you added samples on website?

• No. You can skip this section.
• Yes. Make sure you have added samples following below steps.

1. Find the corresponding markdown file for your new feature in website/docs/documentation folder.
   Make sure you choose the correct class estimators/transformers and namespace.
2. Follow the pattern in markdown file and add another section for your new API, including pyspark, scala (and .NET potentially) samples.
3. Make sure the DocTable points to correct API link.
4. Navigate to website folder, and run yarn run start to make sure the website renders correctly.
5. Don't forget to add <!--pytest-codeblocks:cont--> before each python code blocks to enable auto-tests for python samples.
6. Make sure the WebsiteSamplesTests job pass in the pipeline.

[github-actions]

Hey @memoryz 👋!
Thank you so much for contributing to our repository 🙌.
Someone from SynapseML Team will be reviewing this pull request soon.

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• fix: Fix LightGBM crashes with empty partitions
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[memoryz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (46a1ef8) 86.15% compared to head (0492f43) 86.18%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2131      +/-   ##
==========================================
+ Coverage   86.15%   86.18%   +0.02%     
==========================================
  Files         312      312              
  Lines       16477    16477              
  Branches     1460     1460              
==========================================
+ Hits        14196    14200       +4     
+ Misses       2281     2277       -4     

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[mhamilton723]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[memoryz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).