fix(operator): tolerate missing KEDA when cleaning up ScaledObject (#985)

The VLLMRuntime controller reconciled a stale ScaledObject delete in the
autoscaling-disabled branch, guarding only errors.IsNotFound. On a cluster
without KEDA the keda.sh/v1alpha1 API group is not registered, so the
delete returns a NoKindMatchError rather than NotFound, and every
reconcile failed -- making the operator unusable on clusters that never
requested autoscaling.

Also tolerate meta.IsNoMatchError on the cleanup path: there is nothing to
delete when the CRD is absent, so the reconcile should succeed.

Fixes #981

Signed-off-by: Tai An <antai12232931@outlook.com>