PLANET-6673 we added the funcionality for 2nd level dropdown submenus to the navigation bar. But it's not enabled by default, controlled by a feature flag under Planet 4 > Information architecture. It's time to phase out the feature flag and enable this by default.
- Remove the feature flag from the admin panel.
- Dropdown submenus functionaliy activated by default.
- Remove all obsolete code of this feature flag.