Using multi-attribute Ransack filter not properly creating/pulling label for active filters sidebar content display #7702

When utilizing Ransack's DSL to create an index filter for multiple attributes, ActiveAdmin::Views::ActiveFiltersSidebarContent doesn't properly create or pull the label to display within the active filters sidebar. Instead it pulls the first attribute specified to do a lookup within the ActiveFilter#resource.filters hash. This leads to misleading active filter data within the UI.

For example with the following Rails model:

class Address < ActiveRecord::Base
  #Contains the following attributes:
  # id
  # street_line_1
  # street_line_2
  # city
  # state
  # zip
  # county
end

And a corresponding ActiveAdmin object with a filter searching across city and county:

ActiveAdmin.register Address do
  filter :city_or_county, as: :string, label: 'City or county'
end

Expected behavior

When the city_or_county filter is utilized, I expect the active filters sidebar content to include an item with the label configured for the city_or_county filter (i.e. City or county) by utilizing the entirety of the filter (each attribute, any association, etc...) in order to build or properly lookup the correct filter metadata

Actual behavior

The active filters sidebar content includes an item with only the name of the first attribute accounted for "City". Furthermore, if there was a custom label for the "city" filter, it would pull that filter's label.

How to reproduce

./app/models/address.rb

class Address < ActiveRecord::Base
  #Contains the following attributes:
  # id
  # street_line_1
  # street_line_2
  # city
  # state
  # zip
  # county
end

./app/admin/addresses.rb

ActiveAdmin.register Address do
  filter :city_or_county, as: :string, label: 'City or county'
end

Start a rails server and utilize the filter... If the server started at http://localhost:3000, hitting the following URL would exercise the filter and show the output http://localhost:3000/admin/addresses?q[city_or_county_contains]=ma&commit=Filter&order=id_desc