[clang-tools-extra] [clang-tidy] Add modernize-default-arg-braced-init check (PR #203474)

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AntonyCJ30 wrote:

I have now disabled both 'Copilot code review' and 'Automatic Copilot code review' in my GitHub Copilot settings. Thank you for your guidance on the LLVM AI policy.

Could you please continue with the review? All suggested changes have been addressed. Thank you!

https://github.com/llvm/llvm-project/pull/203474