Refactor stsSetupHostAliases for conditional host aliases

[HighWatersDev]

This PR is meant to fix an issue with Gatekeeper denying the request due to host aliases being passed, even though it's an empty list.

E1007 1932.297598 1 statefulset-reconciler.go:364] doCreateStatefulSet():Host:0-0[0/0]:example/example-clickhouse:StatefulSet create failed. err: admission webhook "validation.gatekeeper.sh" denied the request: [podsecurity] Pods cannot specify host aliases

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