Updated interventions/regions not loaded in UI

[steven-cd]

The lists of interventions and regions are cached in web-ui/pages/simulations/new.tsx for "the life of the server process". This means that if the database is updated (e.g. by script/fetch-recorded-data), the new interventions don't actually appear. I've only been reliably able to update it by restarting the container. I suspect this is something that worked without issue when the UI was hosted on Vercel, and therefore serverless, but not now we have a persistent container. It would also be worth looking to see if other pages do similar things.

[steven-cd]

Discussed that the data being cached is likely not to be that big, and so simplest fix to try first is to remove the cache and see if there is any major impact. Failing that, can try to cache for a fixed period of time