Investigate where the form_builder_service can be improved with caching

[dleard]

The form_builder_service could probably be optimized by caching some of the queries. Several of the queries are returning data that won't change in a short period of time (ie: ConfigurationElements). When passed several source-types worth of data, the build-form-schema endpoint can start to become very slow.

The delay in server response & quickly checking/unchecking source types can cause confusing results. Could also consider disabling the checkboxes until the response has come bac

Developer Checklist:

• investigate where caching might help in the form-builder-service
• implement the optmizations
• check django-silk when hitting that endpoint with several source-types (suggest OG Extraction, it has > 20 potential source types)
• consider disabling checkboxes on check/uncheck until server has responded

[dleard]

@Sepehr-Sobhani @pbastia I've noticed that the build-form-schema endpoint gets quite slow when selecting several source types at a time (up until now, we've only ever had 3 source types maximum, but OG Extraction has >20 potential source types) so I've made this card to investigate how we can optimize that service.