Fix database password clearing when modifying key file / hardware key

[c4rlo]

Fix a bug in the database key settings dialog, where it was previously always incorrectly applying an empty password if the password was not changed but some other change was made (e.g. adding or removing a key file).

Fixes #10996.

I think this bug may have been introduced in #10821, specifically the change to PasswordEditWidget::isEmpty() here.

Testing strategy

Manual testing.

I can try to add an automated test if desired.

Type of change

• ✅ Bug fix (non-breaking change that fixes an issue)

[droidmonkey]

Ugh and I tested this too... must have screwed myself over. I recommend also adding to the GUI tests for this widget to verify this situation doesn't occur in the future.

[droidmonkey]

@phoerious this bug is a breaker... it could cause the end user to be forced into a no-password database credential. They basically have to edit the database password and set it to the original value to change the key file or hardware key.

[jgehrcke]

Just ran into this -- when will we have a new release?

Thanks for all the work on this piece of software. I have so far been using the original with the Mono runtime on Linux (for more than a decade) and am now exploring to using this here instead on Linux. More or less good impression so far, but to be quite honest I wish there were more frequent releases.

[droidmonkey]

It's in immediate pipeline right now.

[jgehrcke]

Thank you so much. Great, important work.