Commands sent by another node before the local node joined are not ignored properly

This is related to ISPN-3731. Commands that were sent by another node before the local node joined were supposed to be ignored in InboundInvocationHandler.

But the ISPN-3731 fix was incomplete, and old commands are still executed on the joiner - although the response is sent to the originator before the command is executed.

I believe this was causing random failures in ReplCommandForwardingTest.