* Use cert-manager to generate certs for tests
* Install Cert-Manager in test env
### Motivation
Currently, we use hard coded certificates for the tests. Instead, we can use Cert Manager to generate the certificates. The primary benefit of this change is that it ensure we're testing the cert manager integration.
### Modifications
* Remove `.ci/tls` directory since we no longer need these certs.
* Remove `scripts/pulsar/clean_tls.sh` (it wasn't used)
* Remove `scripts/pulsar/upload_tls.sh` since we are not uploading any certs
* Update the `helm.sh` test script
* Update the `.ci/clusters` configurations to generate the relevant cert manager manifests
### Verifying this change
- [ ] Make sure that the change passes the CI checks.
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