[PromptFlow] Fix can't raise exception in processpool's run.

[Hhhilulu]

Description

Problem
The wait() method of starmap_async only waits for the result and does not capture exceptions.

Solution:
Use async_result.get() to propagate exceptions if they are raised.

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.
• Create an issue and link to the pull request to get dedicated review from promptflow team. Learn more: suggested workflow.

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]

SDK CLI Global Config Test Result luluzuo/fix_async_starmap

2 tests   2 ✔️  1m 3s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit aef128e.

♻️ This comment has been updated with latest results.

[github-actions]

Executor Unit Test Result luluzuo/fix_async_starmap

563 tests   562 ✔️  49s ⏱️
    1 suites      1 💤
    1 files        0 ❌

Results for commit aef128e.

♻️ This comment has been updated with latest results.

[github-actions]

Executor E2E Test Result luluzuo/fix_async_starmap

140 tests   136 ✔️  2m 26s ⏱️
    1 suites      4 💤
    1 files        0 ❌

Results for commit aef128e.

♻️ This comment has been updated with latest results.

[github-actions]

SDK PFS E2E Test Result luluzuo/fix_async_starmap

  2 files    2 suites   49s ⏱️
  9 tests   9 ✔️ 0 💤 0 ❌
18 runs  18 ✔️ 0 💤 0 ❌

Results for commit aef128e.

♻️ This comment has been updated with latest results.

[github-actions]

promptflow SDK CLI Azure E2E Test Result luluzuo/fix_async_starmap

    2 files      2 suites   1m 57s ⏱️
  99 tests   77 ✔️ 22 💤 0 ❌
198 runs  154 ✔️ 44 💤 0 ❌

Results for commit aef128e.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Test Result luluzuo/fix_async_starmap

2 files  2 suites   20s ⏱️
1 tests 1 ✔️ 0 💤 0 ❌
2 runs  2 ✔️ 0 💤 0 ❌

Results for commit aef128e.

♻️ This comment has been updated with latest results.