[Upgrade] Rebalance failed while swap rebalancing upgraded node with an old version node

Steps to reproduce -

1. Create a 5 node cluster, with 2 nodes with KV, N1QL, Index and other 3 nodes with CBAS. (Version - 7.2.3-6705-enterprise)
2. Create few KV buckets, analytics scopes and collections.
3. Swap rebalance the CBAS CC node first.
4. Swap rebalance the other nodes of the cluster.
5. While swap rebalancing the last node in the cluster, the rebalance fails with following error -

6. Rebalance exited with reason {service_rebalance_failed,cbas,

   {worker_died,

   {'EXIT',<0.20537.1>,

   {rebalance_failed,

   {service_error,

   <<"Rebalance ee711d12e1cc5cfb365bbb2da87b26dd failed: timed out waiting for all nodes to join & cluster active (missing nodes: [], state: UNUSABLE)">>}}}}}.

   Rebalance Operation Id = 10ffeaf5f0fe37f07d3b1c48fefb5adb