not run Capybara tests on the CI server (#12822)
prevent UI test failure randomly
increase Capybara.default_wait_time from 12 to 20 (#12822)
increase Capybara.default_wait_time from 7 to 12 (#12822)
shorten comment lines at test/ui/base.rb
use database_cleaner (#12822)
increase Capybara.default_wait_time from 6 to 7 (#12822)
