Remove AksPreviewIngressProfileInjector reflection shim once Azure.Provisioning.ContainerService surfaces ManagedClusterIngressProfile publicly

## Summary

`Aspire.Hosting.Azure.Kubernetes` ships an internal reflection shim — `AksPreviewIngressProfileInjector` — that pokes the AKS preview-only `properties.ingressProfile.gatewayAPI.installation` and `properties.ingressProfile.applicationLoadBalancer.enabled` Bicep properties onto `ContainerServiceManagedCluster`. This is required to enable AGC + Gateway API on AKS today (see [#16990](https://github.com/microsoft/aspire/pull/16990)), but it's not the long-term shape we want.

The shim is unavoidable today because `Azure.Provisioning.ContainerService 1.0.0-beta.6` is generated against the stable AKS REST schema, where `ingressProfile` has only the single `webAppRouting` child. The SDK code generator's "single-property wrapper collapse" then marks `ManagedClusterIngressProfile` as `internal` and hoists `webAppRouting` directly onto the parent, leaving no public typed surface for `gatewayAPI` / `applicationLoadBalancer`.

We tried two reflection-free alternatives (subclass `ContainerServiceManagedCluster` + deep `DefineProperty` path, and the same plus `DefineModelProperty` graft of a public `ProvisionableConstruct`). Both empirically shadow the typed `Properties` declaration and drop sibling Bicep blocks (`dnsPrefix`, `agentPoolProfiles`, `oidcIssuerProfile`, `securityProfile`). See xmldoc on `AksPreviewIngressProfileInjector` for the details.

## Upstream tracking

Filed against `Azure/azure-sdk-for-net`: [Azure/azure-sdk-for-net#59225](https://github.com/Azure/azure-sdk-for-net/issues/59225)

That issue acknowledges this can't really be fixed in `Azure.Provisioning.ContainerService` until the AKS REST API surfaces the `ingressProfile` additions in a stable version. `Azure.Provisioning.*` is generated against stable schemas as a policy choice across the family.

## What we should do here

When the upstream package next exposes `ManagedClusterIngressProfile` publicly (via stable AKS GA of these preview features, or a preview-targeted regen), we should:

1. Delete `src/Aspire.Hosting.Azure.Kubernetes/AksPreviewIngressProfileInjector.cs`.
2. Replace the `Inject(...)` call in `AzureKubernetesEnvironmentExtensions.ConfigureAksInfrastructure` with the standard public-subclass / typed-property pattern used by `ContainerAppEnvironmentDotnetComponentResource`, `CosmosDBSqlRoleAssignment_Derived`, and `PublicHostingCognitiveServicesCapabilityHostProperties`.
3. Drop the preview `ResourceVersion` override on `ContainerServiceManagedCluster` if the typed properties land in the stable API version.

Until then this issue is the durable subscription point so we get notified when the package update lands.

## Priority

Medium. The current reflection shim is well-tested and the xmldoc is explicit about what it does and why. The only ongoing risk is an upstream `Azure.Provisioning.ContainerService` minor version bump silently changing reflection-visible names (the shim's exception text instructs the maintainer where to look if that happens).