Context:

There are several report types that allow users to specify bucket size/unit, for example date report or number/date variable reports. Currently, this unit is defined in inconsistent locations: for date reports, the unit is set within the GroupByDto/DistribytedByDto, whereas for variable reports, the unit is the bucket size is stored in the report configuration. In the UI, you sometimes select the unit in a third dropdown in the "groupBy" section (e.g. reports grouped by start date -> year) and sometimes in the config menu (e.g. distributed by date variable reports). This should be aligned so the unit is in a consistent place, both in terms of UI and where it's stored in the backend.

AT:

• The bucket unit/size for reports is stored in a consistent place
• The documentation is updated accordingly
• The frontend is updated accordingly