Drop unused init.h includes

These were entirely unused, as based on successful compilation
and a grep for:
  \bStartShutdown\(\)|\bShutdownRequested\(\)|\bInterrupt\(\)|\bShutdown\(\)|\bInitLogging\(\)|\bInitParameterInteraction\(\)|\bAppInitBasicSetup\(\)|\bAppInitParameterInteraction\(\)|\bAppInitSanityChecks\(\)|\bAppInitLockDataDirectory\(\)|\bAppInitMain\(\)|\bSetupServerArgs\(\)|\bLicenseInfo\(\)|g_wallet_init_interface|init.h

src/qt/signverifymessagedialog.cpp

@@ -10,7 +10,6 @@
 #include <qt/platformstyle.h>
 #include <qt/walletmodel.h>
 
-#include <init.h>
 #include <key_io.h>
 #include <validation.h> // For strMessageMagic
 #include <wallet/wallet.h>