refactor: remove tool choice in model callback input

[N3kox]

What type of PR is this?

refactor: remove tool_choice in model callback input

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[github-actions]

⚠️ Breaking API Changes Detected

This pull request contains breaking API changes that may affect compatibility:

uncompatible api changes found: 
github.com/cloudwego/eino/components/model
  Incompatible changes:
  - CallbackInput.ToolChoice: removed

Required Actions:

1. Please review these changes carefully
2. Update the user documentation to reflect these API changes
3. Add a note in the changelog about these breaking changes

[github-actions]

📊 Coverage Report:

File coverage threshold (20%) satisfied:	PASS
Package coverage threshold (30%) satisfied:	PASS
Total coverage threshold (75%) satisfied:	PASS
Total test coverage: 82.7% (2966/3586)