Ladybird/Qt: Show the tab bar by default

We currently only show the tab bar when we have more than one tab open.
This has caused confusion in the past, as it's a bit less obvious that
the browser supports tabs. For example:

https://hackaday.com/2023/10/10/jennys-daily-drivers-serenityos-and-in-particular-ladybird/
"it’s a single window with no tabs"

Ladybird/Qt/TabBar.cpp

@@ -31,7 +31,6 @@ TabWidget::TabWidget(QWidget* parent)
     setDocumentMode(true);
     setElideMode(Qt::TextElideMode::ElideRight);
     setMovable(true);
-    setTabBarAutoHide(true);
     setTabsClosable(true);
 
     installEventFilter(parent);