Remove environment setup list

[notnotdrew]

It was only being used by learn-doctor, which is now deprecated. Then endpoint is also being removed from the Learn API.

learn-web/lib/learn_web/client/environment.rb

Lines 15 to 19 in 1d6928b

	def environment_setup_list
	response = get(environment_setup_list_endpoint)
	LearnWeb::Client::Environment::SetupList.new(response)
	end

and

learn-web/lib/learn_web/client/environment.rb

Lines 7 to 9 in 1d6928b

	def environment_setup_list_endpoint
	"#{API_ROOT}/environmentalizer/steps"
	end