fix datepickers to show correct minDate

[MegaphoneJon]

https://lab.civicrm.org/dev/core/-/issues/2052

(This is against the RC, otherwise identical to #18522)

Overview

#16610 enforces a requirement that datepickers pass dates in Y-m-d format. Some datepickers currently pass a Unix timestamp.

Before

At certain times of day, these datepickers show a minimum year thousands of years in the future.

After

Minimum year is 2020 (and counting).

Comments

Depending on the time of day, this bug won't manifest in the UI. If the code in #16610 results in a date like "0255-09-18" then it's ignored. To test if the bug is present, check the value of $extra['minDate'] after it passes through this line from #16610. If the date isn't today's date, the bug is present.

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).

[colemanw]

I thought that #16610 was passing the min and max dates through strtotime(). Does that function not work with timestamps?

[MegaphoneJon]

Evidently not, hence the bug. From the docs: "The function expects to be given a string containing an English date format and will try to parse that format into a Unix timestamp"

[colemanw]

Ok. This works. Theoretically the string "now" would also work. But this is fine. Thank you for the fix.
I've changed the base to 5.30 because I agree this is a regression we should fix in the RC.

[eileenmcnaughton]

Unrelated fail I believe