Revert "(Fix) Replace OpenStruct with a plain Struct to solve loading…

… issue"

This reverts commit 5f3b67d.

This is now fixed generally by requiring OpenStruct in the main
`application.rb` file:

```
require "ostruct"
```

app/models/concerns/teamable.rb

@@ -26,9 +26,5 @@ module Teamable
     def regional_teams
       REGIONAL_TEAMS.values
     end
-
-    def user_teams
-      USER_TEAMS.values
-    end
   end
 end

app/models/user.rb

@@ -71,8 +71,7 @@ def add_new_project
   end
 
   def team_options
-    team_struct = Struct.new(:id, :name)
-    User.user_teams.map { |team| team_struct.new(team, I18n.t("user.teams.#{team}")) }
+    User.teams.keys.map { |team| OpenStruct.new(id: team, name: I18n.t("user.teams.#{team}")) }
   end
 
   private def apply_roles_based_on_team