Change branch_routing setting to group_enabled

Change the value of the feature setting for branch_routing to be
enabled_by_group instead.

This will allow the flag to be set per group in environments which have
not overridden it.

Author: thomasiles

config/settings.yml

@@ -1,7 +1,8 @@
 # Used to add feature flags in the app to control access to certain features.
 features:
   groups: true # Do not switch off!
-  branch_routing: false
+  branch_routing:
+    enabled_by_group: true
 
 forms_api:
   # Authentication key to authenticate with forms-api

spec/config/settings_spec.rb

@@ -23,7 +23,7 @@
     features = settings[:features]
 
     include_examples expected_value_test, :groups, features, true
-    include_examples expected_value_test, :branch_routing, features, false
+    include_examples expected_value_test, :branch_routing, features, { "enabled_by_group" => true }
   end
 
   describe "forms_api" do