Rejoining member can make other member forget remotely registered RPC

This manifests as a failure controller-csit-3node-drb-partnheal-longevity-only-carbon/8.

It is a longevity test, the failure happened in iteration 4. Member-1 and member-2 had registered RPC implementations (returning constant-1 and constant-2 respectively). Member-3 did not have any implementation registered, and at the start of iteration, it was returning constant-2.
The test then isolates member-2 and waits for member-3 to start returning constant-1.

It is expected that after member-2 rejoins, member-3 should keep responding with constant-1, but the test encountered [0] 501.

I suspect this recent fix [1] is the cause, and should be fixed.

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-drb-partnheal-longevity-only-carbon/8/archives/log.html.gz#s1-t1-k3-k1-k1-k1-k1-k1-k1-k2-k1-k1-k6-k1-k1-k1-k1-k1-k1-k1-k1-k1-k1-k3-k1-k1-k1-k2-k1-k4-k7-k1
[1] https://git.opendaylight.org/gerrit/56783