BgpPeer instantiated twice in clustered configuration

For some reason, in a clustered configuration, BgpPeer is instantiated twice, leading to service failure.

I've prepared a patch that prevents this from happening (https://git.opendaylight.org/gerrit/c/bgpcep/+/95561) but doesn't solve the root cause of the issue and is a kind of workaround.

Note: I see the same problem happens on the Aluminium release.