MB-8069: Leverage recovery map to transfer vbucket data

Under recovery scenario, we cannot use vbucketmap to figure out
which node to recover data to because there are obsolete or dead
nodes in the server list.
Instead, we can leverge recovery map from StartRecovery response
to figure out the new recovery target.

Change-Id: I1555b9f5ad3b3ccd6d06c33a1896523564e2e6fd