Make replicaCount optional (skip rendering when null)

[egvimo]

Currently, replicas is always rendered in the Deployment manifest based on .Values.replicaCount, which defaults to 1.

This makes it impossible to delegate replica management to other mechanisms (e.g., HPA, KEDA) by unsetting the value.

This change allows:

• Using HorizontalPodAutoscaler without conflicting static replica settings
• Explicitly disabling fixed replica counts

Backward Compatibility

• No change for existing users unless they explicitly set replicaCount: null
• Default behavior (1) remains unchanged by values.yaml

Notes

We intentionally avoid a simple if .Values.replicaCount check to ensure 0 remains a valid value.