[tracing/devkit] start_trace just merge new resources

[zhengfeiwang]

Description

This PR targets to update the behavior of start_trace: when tracer provider is set, does not overwrite it, but merge new resource attributes to the existing one. So that start_trace will not pollute user custom tracer provider.

All Promptflow Contribution checklist:

• The pull request does not introduce [breaking changes].
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.
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General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

promptflow-tracing test result

 12 files   12 suites   10s ⏱️
 48 tests  48 ✅ 0 💤 0 ❌
576 runs  576 ✅ 0 💤 0 ❌

Results for commit a044542.

♻️ This comment has been updated with latest results.

[github-actions]

promptflow SDK CLI Azure E2E Test Result zhengfei/bugfix/not-overwrite-trace-provider

  4 files    4 suites   4m 2s ⏱️
205 tests 185 ✅ 20 💤 0 ❌
820 runs  740 ✅ 80 💤 0 ❌

Results for commit a044542.

♻️ This comment has been updated with latest results.

[github-actions]

Executor E2E Test Result zhengfei/bugfix/not-overwrite-trace-provider

223 tests   221 ✅  6m 13s ⏱️
  1 suites    2 💤
  1 files      0 ❌

Results for commit a044542.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Global Config Test Result zhengfei/bugfix/not-overwrite-trace-provider

3 tests   3 ✅  43s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit a044542.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Test Result zhengfei/bugfix/not-overwrite-trace-provider

   12 files     12 suites   47m 50s ⏱️
  566 tests   547 ✅ 19 💤 0 ❌
2 264 runs  2 188 ✅ 76 💤 0 ❌

Results for commit a044542.

♻️ This comment has been updated with latest results.

[github-actions]

Executor Unit Test Result zhengfei/bugfix/not-overwrite-trace-provider

771 tests   771 ✅  3m 45s ⏱️
  1 suites    0 💤
  1 files      0 ❌

Results for commit a044542.

♻️ This comment has been updated with latest results.