Remove window hints clearing the flag Qt::WindowContextHelpButtonHint,
which is already off by default in Qt 6.
In Qt 5 this flag was set by default for QDialogs, and on Windows put a
? button in the corner of the title bar allowing users to activate Qt's
QWhatsThis help system for a given widget. Since we don't set that text
the ? button was useless and so we hid it manually.
This reverts the parts of commit c8c9928eb1 that made translatability
worse rather than better. Changing "Error in column %2" to "%1 in column
%2" not only means that the translators have to check the i18n comments
to know what word hides behind %1, but there's also the problem that
the translator might need to translate "Error" in this context
differently from the standalone string "Error". Having to copy-paste
some HTML tags may be annoying for translators, but it's a far less
serious problem.