[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
usr/lib/PY_VERSION/*-packages/cubicweb/devtools/
usr/lib/PY_VERSION/*-packages/cubicweb/skeleton/
usr/lib/PY_VERSION/*-packages/cubicweb/test
usr/lib/PY_VERSION/*-packages/cubicweb/entities/test
usr/lib/PY_VERSION/*-packages/cubicweb/ext/test
usr/lib/PY_VERSION/*-packages/cubicweb/server/test
usr/lib/PY_VERSION/*-packages/cubicweb/sobjects/test
usr/lib/PY_VERSION/*-packages/cubicweb/hooks/test
usr/lib/PY_VERSION/*-packages/cubicweb/web/test
usr/lib/PY_VERSION/*-packages/cubicweb/etwist/test