event-editor/event-editor-dialog: Always grab focus to summary section

Now that the summary section is always focusable, even when the event is
non-writable, we can make it grab focus every time.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-calendar/-/merge_requests/499>

src/gui/event-editor/gcal-event-editor-dialog.c

@@ -673,8 +673,5 @@ gcal_event_editor_dialog_present_event (GcalEventEditorDialog *self,
 
   adw_dialog_present (ADW_DIALOG (self), parent);
 
-  if (self->writable)
-    gtk_widget_grab_focus (GTK_WIDGET (self->summary_section));
-  else
-    gtk_widget_grab_focus (self->done_button);
+  gtk_widget_grab_focus (GTK_WIDGET (self->summary_section));
 }