chore: Adding SubscriptionKey and Temperature to OpenAIDefaults

[sss04]

Related Issues/PRs

#xxx

What changes are proposed in this pull request?

Adding SubscriptionKey and Temperature to OpenAIDefaults.

How is this patch tested?

• 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.

[mhamilton723]

/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 ✅

Project coverage is 83.98%. Comparing base (79d5b58) to head (d88fab3).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2324      +/-   ##
==========================================
- Coverage   84.44%   83.98%   -0.47%     
==========================================
  Files         328      328              
  Lines       16771    16775       +4     
  Branches     1506     1500       -6     
==========================================
- Hits        14163    14088      -75     
- Misses       2608     2687      +79     

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