Allow short year date format in csv card import

[steffenkleinle]

Is your feature request related to a problem? Please describe.
Previously, it was possibly to import cards with dates in the format dd.MM.yy (e.g. 13.01.25 which should equal 13.01.2025).

Describe the solution you'd like
This behavior seems to not work anymore as the date above is interpreted as 13.01.0025 which obviously leads to a validation error. Restore the old behavior for all date fields.

Describe alternatives you've considered
Only allow dd.MM.yyyy.

Additional context
Discussed here: #1765 (review)

[ztefanie]

This bug is not yet on staging but only on current main. will move this to next up