[feat][CI] Replace the Golang based license_test.go with Apache Rat check in CI

**Is your feature request related to a problem? Please describe.**

There's currently a Golang application to check licenses. This should be replaced with the usage of Apache Rat as we do [in the
release process](https://github.com/apache/pulsar-helm-chart/blob/master/RELEASE.md#prepare-vote-email-on-the-apache-pulsar-release-candidate).

**Describe the solution you'd like**
Switch to use Apache Rat.

**Describe alternatives you've considered**
None.

**Additional context**
- GitHub Actions build job: https://github.com/apache/pulsar-helm-chart/blob/0a45f7786871c2dcf6489fa202abfc083b44a829/.github/workflows/pulsar-helm-chart-ci.yaml#L62-L80
- Apache Rat usage in vote email template: https://github.com/apache/pulsar-helm-chart/blob/master/RELEASE.md#prepare-vote-email-on-the-apache-pulsar-release-candidate