oracle/cluster-manager: pkg/controller/cluster/clustercontroller.go; 16 LoC

Found a possible issue in [oracle/cluster-manager](https://www.github.com/oracle/cluster-manager) at [pkg/controller/cluster/clustercontroller.go](https://github.com/oracle/cluster-manager/blob/7c11d45ed5d1912c86a4faffa15c43dee36ecd4c/pkg/controller/cluster/clustercontroller.go#L503-L518)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first
issue it finds, so please do not limit your consideration to the contents of the below message.

> function call which takes a reference to cluster at line 510 may start a goroutine

[Click here to see the code in its original context.](https://github.com/oracle/cluster-manager/blob/7c11d45ed5d1912c86a4faffa15c43dee36ecd4c/pkg/controller/cluster/clustercontroller.go#L503-L518)

Click here to show the 16 line(s) of Go which triggered the analyzer.

```go
for _, cluster := range clusters.Items {
if clusterStatus, ok := cluster.Annotations[navarkospkgcommon.NavarkosClusterStateKey]; ok {

if clusterStatus == navarkospkgcommon.NavarkosClusterStateProvisioning ||
clusterStatus == navarkospkgcommon.NavarkosClusterStateScalingUp ||
clusterStatus == navarkospkgcommon.NavarkosClusterStateScalingDown {

cc.validateCluster(&cluster, clusterStatus)

} else if clusterStatus == navarkospkgcommon.NavarkosClusterStateJoining {

cc.clusterJoin(&cluster)

}
}
}

```

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commit ID: 7c11d45ed5d1912c86a4faffa15c43dee36ecd4c