[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]