change tektondahboard service type to NodePort

[hakuna-matatah]

Issue #, if available:
#252
#253

Description of changes:

• change service type of tekton-dashboard to Nodeport

testing

- dev-dsk-hakuna-2c-0fa5574b % kubectl get services -n tekton-pipelines
NAME                          TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                              AGE
tekton-dashboard              NodePort    172.20.240.237   <none>        9097:31669/TCP                       31h
tekton-pipelines-controller   ClusterIP   172.20.65.59     <none>        9090/TCP,8008/TCP,8080/TCP           31h
tekton-pipelines-webhook      ClusterIP   172.20.238.21    <none>        9090/TCP,8008/TCP,443/TCP,8080/TCP   31h
tekton-triggers-controller    ClusterIP   172.20.171.72    <none>        9000/TCP                             31h
tekton-triggers-webhook       ClusterIP   172.20.204.191   <none>        443/TCP                              31h

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[felix-zhe-huang]

LGTM