Remove len check in test_unsynced for SyncedList
Remove len check in test_unsynced for SyncedList

This is not necessary as the reference to the list is removed and should
be garbaged collected or destructed along with the C++ object composing
the vector.

joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue