build: fix formatting tasks by ignoring the `zone.js/` directory (#31295)

This was causing issues, because `zone.js` looks like a JS file (despite
it being a directory). The contents of `zone.js/` are still matched by
the globs (it is only the directory itself that is excluded).

Related to #30962.

PR Close #31295

tools/gulp-tasks/format.js

@@ -11,6 +11,7 @@ const {I18N_FOLDER, I18N_DATA_FOLDER} = require('./cldr/extract');
 // clang-format entry points
 const srcsToFmt = [
   'packages/**/*.{js,ts}',
+  '!packages/zone.js',  // Ignore the `zone.js/` directory itself. (The contents are still matched.)
   `!${I18N_DATA_FOLDER}/**/*.{js,ts}`,
   `!${I18N_FOLDER}/available_locales.ts`,
   `!${I18N_FOLDER}/currencies.ts`,