Move Receptive Agents feature to Ultimate

What does this MR do and why?

This MR moves all the Receptive Agents features to Ultimate.

The Receptive Agents features have been introduced in the context of Support clusters that can't see GitLab (&12180) and NOT been released yet. It's also a feature that is NOT available on GitLab.com.

Thus, it's okay to move it to Ultimate.

Commits are individually reviewable.

I'm not sure if it actually makes sense to split into multiple MRs or if it's "simple" enough to review since there is just a pattern of moving files and adding license checks.

Closes #481418 (closed)

app/graphql/types/clusters/agent_type.rb

@@ -66,16 +66,6 @@ class AgentType < BaseObject
         null: true,
         description: 'User access config for the cluster agent.'
 
-      field :is_receptive,
-        GraphQL::Types::Boolean,
-        null: true,
-        description: 'Whether the cluster agent is receptive or not.'
-
-      field :url_configurations,
-        AgentUrlConfigurationType.connection_type,
-        null: true,
-        description: 'URL configurations for the cluster agent in case it is a receptive agent.'
-
       def project
         Gitlab::Graphql::Loaders::BatchModelLoader.new(Project, object.project_id).find
       end
@@ -83,10 +73,6 @@ def project
       def web_path
         ::Gitlab::Routing.url_helpers.project_cluster_agent_path(object.project, object.name)
       end
-
-      def url_configurations
-        [object.agent_url_configuration]
-      end
     end
   end
 end