Unreadable messages from device test dialog on dark theme

1. Open Qt Creator using a dark theme (e.g. Design theme)
2. Open settings/preferences -> devices
3. Add a generic linux device and configure the ssh connection
4. Test the connection

Actual results:
The messages from the testing dialog are very hard to read, black text on gray background.

Expected results:
The dialog should use the same colors as the other output views.