qt: Drop no longer used BitcoinApplication::splashFinished() signal

src/qt/bitcoin.cpp

@@ -312,7 +312,6 @@ void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
     assert(!m_splash);
     m_splash = new SplashScreen(networkStyle);
     m_splash->show();
-    connect(this, &BitcoinApplication::splashFinished, m_splash, &SplashScreen::finish);
 }
 
 void BitcoinApplication::createNode(interfaces::Init& init)

src/qt/bitcoin.h

@@ -89,7 +89,6 @@ public Q_SLOTS:
 Q_SIGNALS:
     void requestedInitialize();
     void requestedShutdown();
-    void splashFinished();
     void windowShown(BitcoinGUI* window);
 
 protected: