[Autoroller] Add // clang-format off to scripts generated by roll_deps and remove outdated .eslintignore comment

Using `.eslintignore` file for `clang-format` is removed in crrev.com/c/2091445 but the comment was still there.

Bug: 40272289
Change-Id: Iad48d3b7414eb373fdc24917ffac79dd331f08ca
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/5285880
Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Auto-Submit: Ergün Erdoğmuş <ergunsh@chromium.org>

scripts/javascript_natives/helpers.js

@@ -225,6 +225,8 @@ export function postProcess(dryRun = false) {
 // Generated from ${
           path.relative(path.join(fileURLToPath(import.meta.url), '..', '..'), fileURLToPath(import.meta.url))}
 
+// clang-format off
+
 ${output}
 `);
 }