feat(llmobs): make model_provider client-specific for the OpenAI integration

[Yun-Kim]

This PR follows up on #10661 by making the model_provider field equal to azure_openai or openai based on the client being used in the span.

The existing release note from #10661 has been updated to include this supplementary change.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/llmobs/_integrations/openai.py                                  @DataDog/ml-observability
releasenotes/notes/feat-openai-azure-23cf45cfa854a5e5.yaml              @DataDog/apm-python
tests/contrib/openai/test_openai_llmobs.py                              @DataDog/ml-observability

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-09-18 18:08:32

Comparing candidate commit 2e30eb8 in PR branch yunkim/llmobs-azure-provider with baseline commit 7a2e802 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 320 metrics, 46 unstable metrics.