Get rid of FreeConsole() call on mariadbd startup

This function has some properties that are not very nice.

• Sometimes, it throws INVALID_HANDLE exception, particularly, when it mariadbd runs under debugger.
• Sometimes, it closes error log in the middle, particularly when debugging service.
• It does not close console, if the console was not created by mariadbd itself
• Ctrl-C stops working, and mariadbd can only be killed "hard" with taskkill /force

The only functionality it provides is remove the window when a GUI application launches mysqld in a user session, but this does not seem to have huge importance. That very same functionality is available with CreateProcess() with dwCreationFlags = CREATE_NO_WINDOW Also available on many scripting languages on Windows, and as a shortcut property for the Windows shortcuts.

Also note, that MySQL 8.0 got rid of FreeConsole() as well.