Trigger "Exit Selection Mode" button on clicked and not on pressed

This way it works just like every other button.

This commit also removes two empty files that sneaked in by
accident.

src/selectionmode/topbar.cpp

@@ -68,7 +68,7 @@ TopBar::TopBar(QWidget *parent) :
     m_closeButton = new QPushButton(QIcon::fromTheme(QStringLiteral("window-close-symbolic")), "", contentsContainer);
     m_closeButton->setText(i18nc("@action:button", "Exit Selection Mode"));
     m_closeButton->setFlat(true);
-    connect(m_closeButton, &QAbstractButton::pressed,
+    connect(m_closeButton, &QAbstractButton::clicked,
             this, &TopBar::selectionModeLeavingRequested);
 
     QHBoxLayout *layout = new QHBoxLayout(contentsContainer);