In the `entrypoint.sh` script, we check if the MongoDB in use, has
replicaSet initiated or not. This is usually done with a `rs.initiate()`
on the cluster.
We need the replicaSet to be enabled on MongoDB, since the backend
server relies on MongoDB `changeStream`s, which is a feature, only
available if replicaSet is enabled.
However, to use the `changeStream` APIs, having the `read` or
`readWrite` role on MongoDB is enough. But the check we do in
`entrypoint.sh`, runs `rs.status()` to see if `replicaSet` is initiated.
This `rs.status()` call, unfortunately, requires the `ClusterMonitor`
role, unlike the `changeStream` API.
To tackle this, we created the `appsmithctl check_replica_set` command.
This command would attempt to use the `changeStream` API, and report
success or failure. But this failed on certain configurations, where
MongoDB was running as a single-node-cluster, on localhost, or a
local/internal network. This was an edge case.
That edge case is solved by this PR. With this, we can use `appsmithctl
check-replica-set` in the `entrypoint.sh` again.
