[BUG] Fix default partition

[charles-typ]

Currently, we are not actually using the default partition because whenever we destroy a partition and build a default partition on top of it, the client map would be removed, therefore the default partition message "!block_moved" could not reach the request client anyway. We use sending a failure message(seq -1) to end the connection.

This approach conflicts with fault tolerance, since we can't differentiate an adversary sending a message with all (seq -1) from we consciously want to end the connection.