Let WP routes all have the same parent routes to avoid that the back button adds a synchronisation between `work-packages` and `work-packages.show` (which alone is not a valid route)

frontend/src/app/features/work-packages/routing/work-packages-routes.ts

@@ -109,7 +109,7 @@ export const WORK_PACKAGES_ROUTES:Ng2StateDeclaration[] = [
     url: '/:tabIdentifier',
     component: WpTabWrapperComponent,
     data: {
-      parent: 'work-packages.show',
+      parent: 'work-packages',
       menuItem: menuItemClass,
     },
   },
@@ -131,7 +131,7 @@ export const WORK_PACKAGES_ROUTES:Ng2StateDeclaration[] = [
       'content-left': { component: WorkPackageListViewComponent },
     },
     data: {
-      parent: 'work-packages.partitioned',
+      parent: 'work-packages',
       bodyClasses: 'router--work-packages-partitioned-split-view',
       menuItem: menuItemClass,
       partition: '-left-only',

frontend/src/app/shared/components/calendar/openproject-calendar.module.ts

@@ -48,7 +48,6 @@ export const CALENDAR_ROUTES:Ng2StateDeclaration[] = [
     data: {
       bodyClasses: 'router--work-packages-calendar',
       menuItem: menuItemClass,
-      parent: 'work-packages',
     },
   },
 ];