Improve filter_category when category in multiple groups [7.5hrs]

[dracos]

If a category is in multiple parent categories, e.g. https://report.peterborough.gov.uk/?filter_category=Broken+glass then the filter on the map works, but when a report is started no category is selected. I guess at least it should select the correct child categories if a correct top level category is picked, could it do more? (raised at https://mysocietysupport.freshdesk.com/a/tickets/1804)

[jacquelinebylau]

https://plan.toggl.com/#timeline/317959/tasks/33843158/embed

[nephila-nacrea]

Left some possibly relevant comments in https://github.com/mysociety/fixmystreet/issues/4282#issuecomment-1446653673