* Imrpove documentation and testing for PodMonitors
* Fix missed references and a typo
### Motivation
Before upgrading to 3.0.0, we want to make sure the kube-prometheus-stack is well documented.
### Modifications
* Update tests and examples to fully disable `PodMonitors` and the installation of the kube-prometheus-stack CRDs.
### Verifying this change
The current tests will cover these changes.
Related to #311
### Motivation
In #299, I updated the values without also updating the test values. As a result, I unintentionally enabled the monitoring stack in the tests and broke some examples. Because we are deploying all resources to a single node. It is possible that we are resource constrained, so I am going to re-disable the monitoring stack.
### Modifications
* Update test cluster configurations to re-disable deploying the monitoring stack
* Update examples with the new configuration
### Verifying this change
- [ ] Make sure that the change passes the CI checks.
* 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.
