When using cli to add node, there can potentially be a race condition in
which all nodes presenting cluster state o.k even though the added node
did not yet meet all cluster nodes.
this adds another utility function to wait until all cluster nodes see the same cluster size
A timing issue like this was reported in freebsd daily CI:
```
*** [err]: Sanity test push cmd after resharding in tests/unit/cluster/cli.tcl
Expected 'CLUSTERDOWN The cluster is down' to match '*MOVED*'
```
We additionally wait for each node to reach a consensus on the cluster
state in wait_for_condition to avoid the cluster down error.
The fix just like #10495, quoting madolson's comment:
Cluster check just verifies the the config state is self-consistent,
waiting for cluster_state to be okay is an independent check that all
the nodes actually believe each other are healthy.
At the same time i noticed that unit/moduleapi/cluster.tcl has an exact
same test, may have the same problem, also modified it.
