Adding option to enable/disable NETINFO variable in Kibana installation steps

[gizas]

Describe the feature:
Kibana offers the following page to install kubernetes manifests in managed mode

In the background this is the ts file that Kibana uses to render for the managed and standalone manifests:
https://github.com/elastic/kibana/blob/65d3d5c7e7baabbcd3d9e99fa507792cba5db1aa/x-pack/plugins/fleet/server/services/elastic_agent_manifest.ts

For example the VESRSION text is rendered with the actual version of ES stack:
image: docker.elastic.co/beats/elastic-agent:VERSION
in line 51

We propose a new variable inside kubernetes that will render NETINNFO:false that is intrdused in following PR: elastic/elastic-agent#3354

Related stories:

• Updating Elastic Manifests with NETINFO variable elastic-agent#3354
• Consider not adding host.ip metadata to k8s container metrics by default integrations#6674
• Add Kubernetes in platforms selection list && update managed agent installation steps #136109

[elasticmachine]

Pinging @elastic/unified-observability (Team:Observability)