Update the Ending Criteria Date Format to "Month Day, Year"

[zackcl]

Version where bug was found:
5.2.0

Describe the bug
This is a low-priority issue, but I think it would be better to update the Ending Criteria date format to "Month Day, Year" (e.g., May 31, 2024) instead of "31st May 2024." We might also want to include the time.

To Reproduce
Steps to reproduce the behavior:

1. Go to the experiment details page.
2. Set the Status to "Scheduled."
3. Set the Ending Criteria by date/time.
4. Observe that the date formats differ between the two.

Expected behavior
The date format should be consistent across the app (ideally).

Screenshots