Operator renders charts using wrong Kubernetes version [maistra 2.2]

When rendering Helm charts, the operator passes in a hard-coded value for KubeVersion (see [1]). In some charts ([2] and now also [3]), the rendered resource depends on this version, so we must ensure that it matches the actual server version.

[1] https://github.com/Maistra/istio-operator/blob/d6c8a08b2cd839bd655bd8b8ae847a0cedfea2c1/pkg/controller/common/helm/helm.go#L52
[2] https://github.com/Maistra/istio-operator/blob/120bd58907ef259f3054559acf67c4ebc793b1dc/resources/helm/v2.2/gateway/templates/deployment.yaml#L53
[3] https://github.com/Maistra/istio-operator/blob/120bd58907ef259f3054559acf67c4ebc793b1dc/resources/helm/v2.2/gateways/istio-egress/templates/autoscale.yaml#L3