fix tests after UI removals in journey detail

- MapSettingsTab: relax Save Map assertion to objectContaining so the new
  mapbox_* defaults don't fail a legacy exact-match expectation.
- JourneyDetailPage: skip tests tied to removed UI (right-column sidebar
  with Synced Trips / Contributors / Journey Stats, Map tab, "Live" and
  "Synced with Trips" hero badges, "Back to Journey" text link). These
  features moved into the settings dialog or were intentionally dropped
  per UX pass and no longer have DOM targets to assert against.
- FE-016: updated to use getByLabelText since the back button is now
  icon-only with aria-label.
- FE-060: drop the sticky-selector check on day headers (header is no
  longer sticky — the presence of the formatted date is sufficient).

client/src/components/Settings/MapSettingsTab.test.tsx

@@ -123,12 +123,12 @@ describe('MapSettingsTab', () => {
     });
     render(<MapSettingsTab />);
     await user.click(screen.getByText('Save Map'));
-    expect(updateSettings).toHaveBeenCalledWith({
+    expect(updateSettings).toHaveBeenCalledWith(expect.objectContaining({
       map_tile_url: '',
       default_lat: 48.8566,
       default_lng: 2.3522,
       default_zoom: 10,
-    });
+    }));
   });
 
   it('FE-COMP-MAP-013: Save Map button shows spinner while saving', async () => {