text: Title: Navigation bar vanishes in case of protected event in an otherwise unprotected category for logged in user
  Body: **Describe the bug / how to reprocess**
  Maybe it's a feature, not a bug, but I'll leave it here, as I find it mildly annoying :sweat_smile: 
  
  I'm logged in to our Indico instance and can see all the categories and events that I have the permissions to see, and in each category I can also see protected events but can't open them, which is OK.
  When I click on an unprotected event in an unprotected category (=unprotected when logged in, i.e. I have the rights to see it) I see the navigation bar at the top (Figure 1). If I now use the "go to previous event" (Older Event) or "go to next event" (Newer Event) this works fine, until I reach a protected event, where I see the "Access denied" message and all navigation vanishes (Figure 2). The only option is to go back in the history to the previously visited event, go up to the category, select the next unprotected event in the direction Older / Newer that I want to go, and then I can use the shortcuts to navigate again - until I encounter the next protected event in the category. Example (after navigating to category `Sub category Foo`:
  
  ```
  Home page >> Some Category >> Sub category Foo
  .
  .
  .
  8. Event on Topic A
  7. Event on Topic C
  6. Event on Topic B
  5. Conveners meeting (protected)
  4. Event on Topic A
  3. Event on Topic B
  .
  .
  .
  ```
  
  In this case if I start at event 7 by clicking on it, and proceed to go to `Older event` I reach event 6 - fine. If I click `Older event` again, I get to the protected event, get the `Access denied` message, and all of the navigation is gone. I can't just go to the category, nor just simply click `Older event` again to get to event 4 which would be the ideal case. The only way to continue is to go back in browser history as described above. Same if I start at event 1, 2, 3 and click `Newer Event`.
  
  **Expected behavior**
  Ideally, the navigation bar would still be present, even if the event is protected and the `Access denied` message is shown, to allow for easy navigation. It's still clear that I'm not supposed to see the content of that meeting, but I know it is there anyway from the category overview, but at least I can easily go to the older or newer event.
  
  **Screenshots**
  ![grafik](https://github.com/indico/indico/assets/10998617/1ba33be9-db1e-4b93-9b59-499725b8deca)
  Figure 1: Usual navigation bar
  
  ![grafik](https://github.com/indico/indico/assets/10998617/9aa29371-9c27-4b9e-9d34-f6c184c6cd1b)
  Figure 2: For restricted / protected events I don't have the permissions to see
  
  
  I hope the bug description is clear enough. If this is the desired behaviour, I'm happy to learn about the reasons :slightly_smiling_face: 