Operator tries to add pods to cluster before failover leading to a infinite rebalance failure loop

Cluster Setup

• Kind cluster locally run on Mac
• 5 nodes with kv,index,query services
• 1 bucket
• Cluster version : 7.6.1-3200

Steps taken in the scenario

• Created a cluster
• Created 1 bucket
• Deleted 2 pods using 

$kubectl delete pod cb-example-0003

$kubectl delete pod cb-example-0004

• Since the autofailover count was 1, ns-server auto failed over 1 of the pods
• The next pod was not failed over.
• Yet replacement pods of cb-example-0005 and cb-example-0006 were already added to the cluster by the operator
• Rebalances are triggered by the operator. The rebalance fails obviously
• The rebalances are continuously retried and it always fails leading to infinite rebalance retry loop.

Issues

• Before all pods/nodes are auto failed over, the new replacement pods should not be added. There should be a status check to check if the pod is actually failed over or not.
• Rebalance is triggered and the non-failed over pod was ejected in the rebalance. A unresponsive node causes rebalance failures always when ejected. The pod should not be added to eject params without being failed over.

Operator logs : 
https://cb-engineering.s3.amazonaws.com/failover_problem/cbopinfo-20240724T200416+0530.tar.gz
Cluster logs : 
https://cb-engineering.s3.amazonaws.com/failover_problem/collectinfo-2024-07-24T143343-ns_1%40cb-example-0000.cb-example.default.svc.zip
https://cb-engineering.s3.amazonaws.com/failover_problem/collectinfo-2024-07-24T143343-ns_1%40cb-example-0001.cb-example.default.svc.zip
https://cb-engineering.s3.amazonaws.com/failover_problem/collectinfo-2024-07-24T143343-ns_1%40cb-example-0002.cb-example.default.svc.zip
https://cb-engineering.s3.amazonaws.com/failover_problem/collectinfo-2024-07-24T143343-ns_1%40cb-example-0005.cb-example.default.svc.zip
https://cb-engineering.s3.amazonaws.com/failover_problem/collectinfo-2024-07-24T143343-ns_1%40cb-example-0006.cb-example.default.svc.zip
 

 The cao tool and operator images were built locally on this commit

commit c2e920ddbcfa9b4819d47ad81d0a35c359dd1dc6 (HEAD -> master, origin/master, origin/HEAD)

Author: usamah jassat <usamah.jassat@couchbase.com>

Date:   Wed Jul 17 15:11:19 2024 +0100    K8S-3581: don't attempt backend migration when rebalance required

    Change-Id: I2d2b6d6d4f8dbb0a30db5bd54a05631d17631eee

    Reviewed-on: https://review.couchbase.org/c/couchbase-operator/+/212890

    Reviewed-by: Yusuf Ramzan <yusuf.ramzan@couchbase.com>

    Tested-by: Build Bot <build@couchbase.com>