refactor: update stubbing in packs_generator_spec to improve clarity and maintainability

Author: AbanoubGhadban

spec/dummy/spec/packs_generator_spec.rb

@@ -220,7 +220,10 @@ def self.configuration
       before do
         stub_packer_source_path(component_name: components_directory,
                                 packer_source_path: packer_source_path)
-        allow(ReactOnRails::Utils).to receive_messages(react_on_rails_pro?: true, rsc_support_enabled?: true)
+        allow(ReactOnRails::Utils).to receive(:react_on_rails_pro?).and_return(true)
+        allow(ReactOnRailsPro.configuration).to receive_messages(
+          enable_rsc_support: true
+        )
       end
 
       context "when common component is not a client entrypoint" do