Cleanup reference to removed grafana docker image (#13672)
Cleanup reference to removed grafana docker image (#13672)

### Motivation

In #13389, I removed the `apachepulsar/pulsar-grafana` docker image. I missed a reference in our publish scripts. Cleaning that up in this PR.

### Verifying this change

Trivial change.

### Does this pull request potentially affect one of the following parts:

No.

### Documentation
  
- [x] `no-need-doc` 
 
This is an internal change to a script.



merlimat/pulsar,massakam/pulsar,massakam/pulsar,yahoo/pulsar,massakam/pulsar,merlimat/pulsar,yahoo/pulsar,yahoo/pulsar,merlimat/pulsar,merlimat/pulsar,merlimat/pulsar,yahoo/pulsar,yahoo/pulsar,merlimat/pulsar,massakam/pulsar,massakam/pulsar,massakam/pulsar,yahoo/pulsar