[multi-sources-removal] Drop entities.source column Since we remove federated multi-sources support, the same value ('system') is always stored in this column and so could be removed. Also, cleanup repository caches and a few api where the very same useless information could be removed. Closes #2919300, at last [jcr: restore sanity check of etype against schema in checkintegrity.has_eid]

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')