[Platform] YW should show metrics for old and new nodes during full move

[rao-vasireddy]

It looks like YW starts showing metrics only for the new nodes at the beginning of the data move for a full move. At this point the old nodes are also part of the cluster and are doing ops. The cutover to new nodes should only happen at the end of the data move. During the data move YW should show metrics for all the nodes that are part of the cluster during that time. On large clusters, the data move can take many hours.

Aha! Link: https://yugabyte-test.aha.io/features/PLATFORM-333