[devtools] Fix database creation issues for CubicWebTestTC tests To reproduce (with a purged repo): * python web/test/test_jscript.py * python web/test/unittest_views_xmlrss.py The '__default_empty_db__' will contain the wrong 'base_url' configuration, thus breaking URLs in the xmlrss tests. Closes #9297611.

usr/lib/python2*/*-packages/cubicweb/entities/
usr/lib/python2*/*-packages/cubicweb/ext/
usr/share/cubicweb/cubes/
usr/lib/python2*/*-packages/cubicweb/*.py