ISPN-2473 Unnecessary forwarding for TxCompletionCommands

The topologyId field was initialized with 0, so RpcManagerImpl wasn't
setting the correct value.
ISPN-2473 Forwarding for non-transactional write commands should be asynchronous

Tests for command forwarding, both for transactional and non-transactional
caches (but only in repl mode for now).