[tests] Move 'anonymous_allowed' property from CubicWebServerTC to CubicWebTC
The effective set of the property on the config is now done later that before,
ie at the end of CubicWebTC.init_config instead of before.
It is believed not to have an impact on the test suites that uses
`anonymous_allowed`.
Related to #4002134
addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile