[UI] Index stats not displayed in a mixed mode cluster

Build : 7.0.0-5016

Steps :
1. Create a 2-node cluster running 6.6.2-9588 with kv+n1ql+index+fts on both the nodes and install all 3 sample buckets
2. Swap rebalance one node from the cluster with a spare node running 7.0.0-5016 with same services.
3. Check the indexes list page from both the nodes of the cluster.

The 6.6.2 page will list all index stats on the list page :

But the 7.0 page will not show any stats on the list page :

This is on a Windows cluster, but I guess this is not OS specific. Should be seen on Linux platforms as well.