Date and Time: specific invalid values can have unexpected results

[ebruchez]

Following #4794.

Enter, for example "2025-01-07T" in the date field. The date field keeps this incorrect value, but the Date and TIme field doesn't show as invalid.

I suspect that we simply remove the T from the string before copying it to the ISO Date and Time value, making the Date and Time valid, while the Date remains invalid.