SyncedIdentity for foreign authorizable always has isGroup set to false

Calling DefaultSyncContext.sync(String userId) for an authorizable that exists but belongs to a different IDP, will return a result with SyncedIdentity that always returns false for SyncedIdentity.isGroup.

I guess this is a copy-paste mistake from the result generated for a null authorizable above. The fix would be trivial by passing Authorizable.isGroup.