qt: Change type and title of "Passwords do not match" notification

* qt/pinentrydialog.cpp (PinEntryDialog::onAccept): Make notification
an "information". Use repeat error text as title.

This makes the type of the messagebox consistent with the messagebox
used for password constraint violations. Additionally, it replaces
the untranslated title with the translated repeat error text (for lack
of a better translated text).

• GnuPG-bug-id: T5543