use only middleware_args in sinatra tests

Author: sergiofbsilva

instrumentation/sinatra/test/opentelemetry/instrumentation/sinatra_dup_http_test.rb

@@ -219,7 +219,7 @@ class CustomError < StandardError; end
       let(:app) do
         apps_to_build = apps
         Rack::Builder.new do
-          use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args_dup)
+          use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args)
 
           apps_to_build.each do |root, app|
             map root do

instrumentation/sinatra/test/opentelemetry/instrumentation/sinatra_stable_http_test.rb

@@ -199,7 +199,7 @@ class CustomError < StandardError; end
       let(:app) do
         apps_to_build = apps
         Rack::Builder.new do
-          use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args_stable)
+          use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args)
 
           apps_to_build.each do |root, app|
             map root do