[test] Remove dead commented servlet_spec code

(cherry picked from commit 1728ca7)

Author: chadlwilson

src/spec/ruby/rack/handler/servlet_spec.rb

@@ -968,7 +968,6 @@ def servlet.create_env(servlet_env)
 
     it "uses custom response class" do
       expect(servlet).to receive(:create_env).and_return({})
-      # expect(app).to receive(:call).and_return([ 200, {}, '' ])
 
       servlet_env = double("servlet request")
       expect(servlet.call(servlet_env)).to be_a Rack::Handler::CustomResponse