AO3-6889 Add rack-timeout gem (#5036) #4999

Job	Run time
rake db:otwseed	1m 13s
rspec spec/controllers	13m 13s
rspec spec/models	5m 33s
rspec --exclude-pattern 'spec/{controllers,models}/*/.rb'	8m 23s
cucumber features/admins	7m 23s
cucumber features/bookmarks	4m 42s
cucumber features/collections	6m 31s
cucumber features/comments_and_kudos	6m 59s
cucumber features/gift_exchanges	6m 48s
cucumber features/importing	2m 40s
cucumber features/other_a	12m 34s
cucumber features/other_b	6m 40s
cucumber features/prompt_memes_a	4m 21s
cucumber features/prompt_memes_b	4m 1s
cucumber features/prompt_memes_c	6m 43s
cucumber features/search	6m 56s
cucumber features/tag_sets	3m 26s
cucumber features/tags_and_wrangling	7m 26s
cucumber features/users	5m 8s
cucumber features/works	12m 9s
	2h 12m 49s

Provide feedback