Merge branch '58969-fix-request-context-spec' into 'master'

Fix test environment pollution in spec/lib/gitlab/request_context_spec.rb

Closes #58969

See merge request gitlab-org/gitlab-ce!26167

(cherry picked from commit ef9b6012)

fcf418d6 Fix test environment pollution in spec/lib/gitlab/request_context_spec.rb

spec/lib/gitlab/request_context_spec.rb

@@ -25,7 +25,7 @@ describe Gitlab::RequestContext do
           [200, {}, ["Hello"]]
         end
-        Rails.application.middleware.build(endpoint).call(env)
+        described_class.new(endpoint).call(env)
         expect(client_ip).to eq(load_balancer_ip)
       end