Fix duplicate VMCP_IMAGE env var in e2e lifecycle workflow

The test-e2e-lifecycle.yml workflow was setting VMCP_IMAGE via
operator.env[0], but PR 2802 added a dedicated operator.vmcpImage
value that gets rendered directly in the deployment template.
This caused duplicate VMCP_IMAGE entries in the env array.

Update the workflow to use the new operator.vmcpImage helm value
instead of the generic operator.env mechanism.

Author: claude

.github/workflows/test-e2e-lifecycle.yml

@@ -102,8 +102,7 @@ jobs:
         helm upgrade --install toolhive-operator deploy/charts/operator \
           --set operator.image=${OPERATOR_IMAGE} \
           --set operator.toolhiveRunnerImage=${TOOLHIVE_IMAGE} \
-          --set-string 'operator.env[0].name=VMCP_IMAGE' \
-          --set-string "operator.env[0].value=${{ env.VMCP_IMAGE }}" \
+          --set operator.vmcpImage=${{ env.VMCP_IMAGE }} \
           --namespace toolhive-system \
           --create-namespace \
           --kubeconfig kconfig.yaml