Refactor all .length === 0 patterns in JS (#30045)

This pattern comes of often during review, so let's fix it once and for
all. Did not test, but changes are trivial enough imho.

web_src/js/features/repo-settings.js

@@ -71,7 +71,7 @@ export function initRepoSettingSearchTeamBox() {
 }
 
 export function initRepoSettingGitHook() {
-  if ($('.edit.githook').length === 0) return;
+  if (!$('.edit.githook').length) return;
   const filename = document.querySelector('.hook-filename').textContent;
   const _promise = createMonaco($('#content')[0], filename, {language: 'shell'});
 }