floss: Re-order AclManager Start/Stop

We need to initialize classic_impl and le_impl before we register for
Dequeue. Otherwise, we may attempt to access those impls before they are
ready. Similarly, unregister before cleaning up the impls for the same
reason.

Bug: 259585527
Tag: #floss
Test: ChromeOS basic autotest
Change-Id: I6f23ac785949dc332ec72a6bfa49b91ae833e41a