[clang-tools-extra] [tool] Remove legacy argument `-ignore-insert-conflict` from `run-clang-tidy.py` (PR #127066)

[Vicente Mataix Ferrándiz via cfe-commits]

loumalouomega wrote:

> Best would be to add that option to script and let user decide whatever use it or not.

Do you want me to do it?

https://github.com/llvm/llvm-project/pull/127066