kill register_appobject_class method, simplifying autoregistration. Update test accordingly (test which manually registers object should also properly call there __register__ method). Drop the disable-appobjects config file entry: no one used it since its introduction years ago.

backport stable branch and some vreg cleanups: * move initialization_completed from cwvreg to base VRegistry class allowing simplification of CWVregistry * cleanup initialization process: __registered__ is now called after initialization completed, by the relevant registry. * fix/remove deprecated tests

fix security issue #36564 (integrity error w/ RQLUniqueConstraint) by using a global lock serializing commit when some RQLUniqueConstraint is encountered.

errors on postcommit should never occurs, log it as critical

missing test data

reminder, cleanup

initialize property once initialization has been fully completed, close #666573