[multi-sources-removal] Drop deleted_entities system table and entities.mtime column since they were only used by the entities_modified_since api of the repository which has been dropped. Along with them, the multi-sources-etypes configuration variable and some sql queries at modification/deletion time of entities. Bon vent ! Related to #2919300

from datetime import datetime

for rtype in ('cw_support', 'cw_dont_cross', 'cw_may_cross'):
    drop_relation_type(rtype)

add_entity_type('CWSourceSchemaConfig')

if not 'url' in schema['CWSource'].subjrels:
    add_attribute('CWSource', 'url')
    add_attribute('CWSource', 'parser')
    add_attribute('CWSource', 'latest_retrieval')