Update the tutorial Monitor Kubernetes

### Description

Our tutorial https://www.elastic.co/guide/en/observability/current/monitor-kubernetes.html is a bit outdated and has some bugs.

We need to review it completely and update it.
The major issue it has is that on the `Part 1` it configures the Kubernetes Integration while in `Part 2` it tells the user to deploy and Standalone Agent, which has no sense.

We need to determine the best way to move this forward and also considering that there are multiple ways to deploy the agents (which is a mess that we are trying to solve also):

- Kibana Add-Data onboarding UX offers now a `kustomize` command that will be deprecated soon (hopefully)
- We are in the process of standarizing the agent deployment via a new Helm Chart (which supports both standalone and fleet managed modes).
- The original `Run Elasticsearch on Kubernetes` doc offers a static manifest.
- Kibana `Kubernetes Integration` UI offers a static manifest also (hopefully the same as the Elastic Agent original doc).

With all the previous in mind we have to make some decisions here. My initial suggestion is:
- Point the customer to a new doc (in Fleet documentation) where we are going to explain the different modes of deploying Elastic Agent.
- Offer in the tutorial the installation in two ways (Fleet Managed and Standalone).
- Also there are some nice details and explanations about the Kubernetes Integration in this document that should probably be located in the `integration` documentation instead of here.
- For the APM part of the doc we need to review it and probably ensure it's also linked from the APM docs (probably via an include and a separate file if it's not done already).

We probably need to consider the `helm chart based installation` or leave the document ready for an easy transition when the helm chart become GA and the default method.

### Resources

N/A

### Which documentation set does this change impact?

Stateful only

### Feature differences

N/A

### What release is this request related to?

N/A

### Collaboration model

The documentation team

### Point of contact.

**Main contact:** @eedugon

**Stakeholders:** @mdbirnstiehl , @bmorelli25 , @kilfoyle