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

[Congcong Cai via cfe-commits]

HerrCai0907 wrote:

> Remove legacy argument `-ignore-insert-conflict` flag from `run-clang-tidy.py`

Could you explain more about `legacy` argument `-ignore-insert-conflict`. It still in `clang-apply-replacements` tool.

```
USAGE: clang-apply-replacements [options] <Search Root Directory>

OPTIONS:

Formatting Options:

  --format                   - Enable formatting of code changed by applying replacements.
                               Use -style to choose formatting style.
  --style=<string>           - Set coding style. <string> can be:
                               1. A preset: LLVM, GNU, Google, Chromium, Microsoft,
                                  Mozilla, WebKit.
                               2. 'file' to load style configuration from a
                                  .clang-format file in one of the parent directories
                                  of the source file (for stdin, see --assume-filename).
                                  If no .clang-format file is found, falls back to
                                  --fallback-style.
                                  --style=file is the default.
                               3. 'file:<format_file_path>' to explicitly specify
                                  the configuration file.
                               4. "{key: value, ...}" to set specific parameters, e.g.:
                                  --style="{BasedOnStyle: llvm, IndentWidth: 8}"
  --style-config=<string>    - Path to a directory containing a .clang-format file
                               describing a formatting style to use for formatting
                               code when -style=file.

Generic Options:

  --help                     - Display available options (--help-hidden for more)
  --help-list                - Display list of available options (--help-list-hidden for more)
  --version                  - Display the version of this program

Replacement Options:

  --ignore-insert-conflict   - Ignore insert conflict and keep running to fix.
  --remove-change-desc-files - Remove the change description files regardless of successful
                               merging/replacing.
```

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