Fixed the preview keyboard shortcut focusing wrong tab

Closes #31101

app/assets/javascripts/shortcuts.js

@@ -57,8 +57,11 @@ import findAndFollowLink from './shortcuts_dashboard_navigation';
 
     Shortcuts.prototype.toggleMarkdownPreview = function(e) {
       // Check if short-cut was triggered while in Write Mode
-      if ($(e.target).hasClass('js-note-text')) {
-        $('.js-md-preview-button').focus();
+      const $target = $(e.target);
+      const $form = $target.closest('form');
+
+      if ($target.hasClass('js-note-text')) {
+        $('.js-md-preview-button', $form).focus();
       }
       return $(document).triggerHandler('markdown-preview:toggle', [e]);
     };

changelogs/unreleased/form-focus-previous-incorrect-form.yml

+---
+title: Fixued preview shortcut focusing wrong preview tab
+merge_request:
+author:

spec/javascripts/shortcuts_spec.js

+/* global Shortcuts */
+describe('Shortcuts', () => {
+  const fixtureName = 'issues/open-issue.html.raw';
+
+  preloadFixtures(fixtureName);
+
+  describe('toggleMarkdownPreview', () => {
+    let sc;
+    let event;
+
+    beforeEach(() => {
+      loadFixtures(fixtureName);
+
+      spyOnEvent('.js-md-preview-button', 'focus');
+
+      event = $.Event('', {
+        target: document.querySelector('.js-note-text'),
+      });
+
+      sc = new Shortcuts();
+    });
+
+    it('focuses preview button in form', () => {
+      sc.toggleMarkdownPreview(event);
+
+      expect('focus').toHaveBeenTriggeredOn('.js-md-preview-button');
+    });
+  });
+});