AO3-6672 Allow some admins to set a generic username #4861

Job	Run time
rake db:otwseed	1m 58s
rspec spec/controllers	12m 55s
rspec spec/models	5m 42s
rspec --exclude-pattern 'spec/{controllers,models}/*/.rb'	8m 17s
cucumber features/admins	8m 34s
cucumber features/bookmarks	4m 56s
cucumber features/collections	5m 55s
cucumber features/comments_and_kudos	6m 54s
cucumber features/gift_exchanges	6m 43s
cucumber features/importing	2m 37s
cucumber features/other_a	11m 30s
cucumber features/other_b	6m 19s
cucumber features/prompt_memes_a	4m 6s
cucumber features/prompt_memes_b	3m 41s
cucumber features/prompt_memes_c	4m 47s
cucumber features/search	6m 22s
cucumber features/tag_sets	3m 11s
cucumber features/tags_and_wrangling	6m 52s
cucumber features/users	5m 16s
cucumber features/works	12m 30s
	2h 9m 5s

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