inbox_ui: Fix empty view text for both channel and normal view visible.

Fixed by hiding inbox view empty text when channel view is visible.
To ensure normal inbox view empty text is hidden, we make it think
there is visible unread topics.

web/src/inbox_ui.ts

@@ -912,7 +912,8 @@ function render_channel_view(channel_id: number): void {
             INBOX_SEARCH_ID,
         }),
     );
-    show_empty_inbox_text(false);
+    // Hide any empty inbox text by default.
+    show_empty_inbox_text(true);
     channel_view_topic_widget = new InboxTopicListWidget(
         $("#inbox-list"),
         channel_id,