### What problem does this PR solve?

change default models to buildin models
https://github.com/infiniflow/ragflow/issues/7774

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

### What problem does this PR solve?

change variable for ZHIPU_AI_API_KEY

### Type of change

- [x] Update test case

### What problem does this PR solve?

use environment variable for ZHIPU_AI_API_KEY

### Type of change

- [x] Test update

### What problem does this PR solve?

This PR introduces Pydantic-based validation for the delete dataset HTTP
API, improving code clarity and robustness. Key changes include:

1. Pydantic Validation
2. Error Handling
3. Test Updates
4. Documentation Updates

### Type of change

- [x] Documentation Update
- [x] Refactoring

### What problem does this PR solve?

Configure test case priorities to reduce CI execution time

### Type of change

- [x] Test cases update

### What problem does this PR solve?

cover [create session with chat
assistant](https://ragflow.io/docs/dev/http_api_reference#create-session-with-chat-assistant)
endpoints

### Type of change

- [x] add test cases

### What problem does this PR solve?

cover [create chat
assistant](https://ragflow.io/docs/v0.17.2/http_api_reference#create-chat-assistant)
endpoints

### Type of change

- [x] add test cases

### What problem does this PR solve?

 Refactor test fixtures and test cases

### Type of change

- [ ] Refactoring test cases

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change

- [x] update test cases

### What problem does this PR solve?

cover [download docments
endpoints](https://ragflow.io/docs/dev/http_api_reference#download-document)

### Type of change

- [x] add test cases

### What problem does this PR solve?

cover upload docments endpoints

### Type of change

- [x] add test cases