NVCA workload config persistence prunes required MiniService spec fields

[sbaum1994]

Problem

Persisting a rendered workload configuration can remove existing required fields from a MiniService spec and permanently wedge reconciliation.

This was reproduced with NVCA 3.1.0 on a BYOC Kubernetes cluster. A Helm workload rendered an nvcf-workload-config ConfigMap containing StatusByWorkerReadiness: true. The chart itself rendered successfully, but the function never completed deployment.

Observed behavior

After NVCA persisted spec.workloadConfig, the live MiniService changed from a complete spec to one where fields including these were empty or absent:

spec:
  namespace: ""
  icmsRequestName: ""

The intended spec.workloadConfig field was also absent.

The MiniService remained in Installing, no workload objects were applied, and the reconciler repeatedly returned:

terminal error: miniservice <name> has no namespace

Deleting the function also left the empty function namespace behind because the invalid MiniService could not reconcile through normal cleanup.

Expected behavior

NVCA should persist only spec.workloadConfig while retaining every existing MiniService field. Reconciliation should then continue and apply the rendered workload objects.

Root cause

Two behaviors interact in this path:

1. pkg/apis/nvca/v1alpha1/miniservice_json.go defines custom JSON serialization for MiniServiceSpec, but its compatibility payload omits WorkloadConfig. The intended field is therefore not serialized or deserialized.
2. internal/miniservice/reconcile.go:saveWorkloadConfig constructs a partial MiniService, then patches it with server-side apply, force ownership, and managedByValue:

r.Client.Patch(ctx, base, client.Apply, client.ForceOwnership, client.FieldOwner(managedByValue))

The custom serializer emits zero values for required fields on that partial object while omitting workloadConfig. The same field manager also owns fields from the original MiniService apply. The result overwrites or prunes required fields such as spec.namespace and spec.icmsRequestName without persisting the intended config.

Suggested fix

Include WorkloadConfig in the MiniServiceSpec compatibility JSON representation, then patch the workload config with a merge patch based on a deep copy of the existing object. This updates only spec.workloadConfig without changing field ownership for the rest of the spec.

Add a regression test that starts with a complete MiniService, saves a non-empty workload config, reads the object back, and verifies that namespace, icmsRequestName, Helm configuration, and other existing spec fields are unchanged.