Do not hide subevent list if filtered list is empty (#6460)

* Do not hide subevent list if filtered list is empty

* Event calendar: Allow to show a message if no events are found

* Apply suggestion from @luelista

Co-authored-by: luelista <weller@rami.io>

* Fix failures on org level

* add aria-hidden if no subevents

* Update src/pretix/base/settings.py

* Update src/pretix/base/settings.py

Co-authored-by: Richard Schreiber <schreiber@pretix.eu>

---------

Co-authored-by: luelista <weller@rami.io>
Co-authored-by: Richard Schreiber <schreiber@rami.io>
Co-authored-by: Richard Schreiber <schreiber@pretix.eu>

src/pretix/control/forms/event.py

@@ -600,6 +600,7 @@ class EventSettingsForm(EventSettingsValidationMixin, FormPlaceholderMixin, Sett
         'imprint_url',
         'checkout_email_helptext',
         'presale_has_ended_text',
+        'event_list_empty_text',
         'voucher_explanation_text',
         'checkout_success_text',
         'show_dates_on_frontpage',
@@ -734,6 +735,7 @@ class EventSettingsForm(EventSettingsValidationMixin, FormPlaceholderMixin, Sett
             del self.fields['event_list_available_only']
             del self.fields['event_list_filters']
             del self.fields['event_calendar_future_only']
+            del self.fields['event_list_empty_text']
         self.fields['primary_font'].choices = [('Open Sans', 'Open Sans')] + sorted([
             (a, FontSelect.FontOption(title=a, data=v)) for a, v in get_fonts(self.event, pdf_support_required=False).items()
         ], key=lambda a: a[0])