[ldap] simplify connection handling since we deleted ldapuser source, we don't need anymore the get_connection and ConnectionWrapper stuff (that was used to put the ldap connection into the cnxset). Also, we should simply let connection errors propagate so this is properly reported to import logs.

[ldap] merge cw.server.ldaputils back into ldapfeed source we don't need separated modules since ldapuser source has been removed

[config] cleanup/refactor server sources file values handling * kill former `sources` method, misnamed since we've only the system source configuration in the sources file (and some default admin account information) * introduce new system_source_config and default_admin_config properties to access to the two information in this file Then use one or the other when appropriate

[repoapi] drop get_option_value's foreid argument repoapi was introduced in 3.19, so no need to introduce legacy deprecated stuff at the same time.

[multi-sources-removal] Drop foreid argument of repo.get_option_value It doesn't need it anymore. Related to #2919300

[c-c restore] drop useless restore-all option, and related systemonly argument

[multi-sources-removal] Kill repo.sources there is only the system source in there now! Related to #2919300

[multi-sources-removal] Drop no more necessary scleanup (source cleanup) argument Related to #2919300

[multi-sources-removal] drop source location search on glob_*[entity|relation] methods source is now always the system source Related to #2919300 [jcr: fix wrong rebase in symmetric relation removal]

[server test] simplify data-schemaserial test instance's schema

[multi-sources-removal] Drop (dont_)cross relation related code That was only needed for now deleted 'true' multisources. Related to #2919300 [jcr: also remove it from server/test/data-schemaserial/schema.py]

[multi-sources-removal] Simplify repo.delete_info_multi arguments, uri is no more used Related to #2919300

[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

[multi-sources-removal] drop repository entities_modified_since public api actually only used by pyrorql/zmqrql sources which have been dropped. This will allow to drop a bunch of system meta-data (eg deleted_entities) Related to #2919300

[multi-sources-removal] Drop the "true" multi-sources planner Only keep copy-based sources. This will soon allow for greater code simplification. Related to #2919300