add tests for prompts with math problems.

[yiranwu0]

Why are these changes needed?

Add test of 17 math problems to "openai" workflow when being deployed. The prompt must solve at least 8/17 problems to pass the test.

Related issue number

Checks

• [ ] I've included any doc changes needed for https://microsoft.github.io/FLAML/. See https://microsoft.github.io/FLAML/docs/Contribute#documentation to build and test documentation locally.
• [ ] I've added tests (if relevant) corresponding to the changes introduced in this PR.
• [ ] I've made sure all auto checks have passed.