feature request to relax the missing data constraint in load_data

[djinnome]

          Approving. Perhaps we should create an issue for a feature request to relax the missing data constraint.

Originally posted by @djinnome in #458 (review)

[djinnome]

Given that we now have to deal explicitly with missing data in the November 2024 epidemiology demo in Scenario 4, perhaps we should revisit this feature request:

Epidemiological data can be imperfect, and you will find that to be the case within these counties. Specifically:
• In County A, City 1, a large chunk of the data is missing due to a month-long issue with the city’s data collection system.
• In County B, City 3, data was not collected regularly, and thus there are gaps missing in the data. About 30% of the timepoints have no data collected for them.
• In County C, City 6, the mayor of the city implemented an intervention 30% of the way through the period to reduce transmission rates even further. The same intervention was not applied in any other county or city.