fix: use gn/clang-format from src (#19145)

* fix: use gn/clang-format from src

* fix: download clang-format in lint job

* chore: fix linting warning

* chore: get_path_in_buildtools => get_buildtools_executable

* chore: the clang-format npm package is not used

script/run-gn-format.py

@@ -2,6 +2,8 @@ import os
 import subprocess
 import sys
 
+from lib.util import get_buildtools_executable
+
 SOURCE_ROOT = os.path.dirname(os.path.dirname(__file__))
 
 # Helper to run gn format on multiple files
@@ -12,9 +14,11 @@ def main():
   new_env['CHROMIUM_BUILDTOOLS_PATH'] = os.path.realpath(
     os.path.join(SOURCE_ROOT, '..', 'buildtools')
   )
+
+  gn_path = get_buildtools_executable('gn')
   for gn_file in sys.argv[1:]:
     subprocess.check_call(
-      ['gn', 'format', gn_file],
+      [gn_path, 'format', gn_file],
       env=new_env
     )