refactor: remove useless function call and refine tests.

[liutongxuan]

No description provided.

[gemini-code-assist]

Code Review

The pull request effectively refactors the JinjaChatTemplate::apply method usage across LLMMaster and RecMaster. By removing the has_tools() check and always calling the apply overload that accepts json_tools, the code is simplified and made more robust. The change in access specifier for the apply overload without json_tools from public to protected improves encapsulation. The introduction of TestableJinjaChatTemplate in the test file is a correct approach to maintain test coverage for the now protected methods. Overall, these changes are a good improvement to the codebase, enhancing maintainability and reducing redundancy.