dapr-apim-integration sample: echo-service and event-subscriber need a tracing config and fail to start

echo-service and event-subscriber have the annotation:

```yaml
dapr.io/config: "tracing"
```

and fail to start as they can't find this config.

Fix:

* Create a tracing config in file `k8s/tracing.config.yaml`:

```yaml
apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
name: tracing
namespace: default
spec:
tracing:
samplingRate: "1"
zipkin:
endpointAddress: "http://zipkin.default.svc.cluster.local:9411/api/v2/spans"
```

```sh
kubectl apply -f k8s/tracing.config.yaml
```

Install Zipkin:

```sh
kubectl create deployment zipkin --image openzipkin/zipkin
kubectl expose deployment zipkin --type ClusterIP --port 9411
```

Redeploy echo-service and event-subscriber.

My environment:

* Dapr 1.5.1
* Kubernetes: v1.21.2