Elixir CookieAuthTest is flakey

[janl]

1) test cookie auth (CookieAuthTest)
     test/elixir/test/cookie_auth_test.exs:215
     Assertion with == failed
     code:  assert resp.status_code() == expect_response
     left:  409
     right: 404
     stacktrace:
       test/elixir/test/cookie_auth_test.exs:178: CookieAuthTest.delete_as/3
       test/elixir/test/cookie_auth_test.exs:286: (test)

I’ll investigate this week, if I can’t solve it, I’ll revert to the JS version.

[kocolosk]

Should be fixed by #2420