Default `-printtoconsole` to false for the GUI. GUI programs should not print to the console unnecessarily. For example, when launched by the window manager, the output might end up in the X session log file,
resulting in duplicate logging. On Windows, it is pointless as well because bitcoin-qt isn't a console application.

This same mechanism is used to set `-server` to true by default for bitcoind: https://github.com/bitcoin/bitcoin/blob/master/src/bitcoind.cpp#L116

(fixes #13004)

make check
./bitcoin-qt