VACMS-19377: Fixed for tabbing on menu systems.

[anantais]

Description

Closes #19377

Testing done

Screenshots

QA steps

When logged in to the Drupal backend, start to tab through the main menus with your keyboard (content, structure, etc).
The tabbing should work on the main menus but require you to hit enter to tab in to submenus.

As user uid with user_role

1. Tab through Drupal back end menus
2. Hit enter to enter a sub menu.
3. If you do not hit enter you should remain in the top level menu when tabbing

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CMS user-facing announcement

Is an announcement needed to let editors know of this change?

• Yes, and it's written in issue ____ and queued for publication.
  • Merge and ping the UX writer so they are ready to publish after deployment
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  • Don't merge yet -- ping the UX writer to write and queue content
• No announcement is needed for this code change.
  • Merge & carry on unburdened by announcements

[github-actions]

Checking composer.lock changes...