[Request]: Update CPU and Network metrics in docs

[roshan-elastic]

Description

We are going to be updating the metric definitions for three existing metrics in Inventory and Hosts:

CPU Usage
Network Inbound
Network Outbound

These are defined as 'inventory' metrics for Hosts and is commonly leveraged by both Inventory and Inventory alerting rules:

In Inventory

In Inventory Rules

Additionally, the Hosts UI has these metrics definitions defined too (but they are not defined in the same place in the code):

To avoid affecting existing rules customers already have, instead of changing the actual metric definitions - we'll create new metrics and refer to the old ones as 'legacy':

For example, for the new 'CPU usage' metric definition we will:

• Update the Hosts UI to use this new one instead of the old one (we'll change the tooltips as well)
• Update the Inventory & inventory alerts to refer to the existing 'CPU usage' metrics as 'CPU Usage (legacy)'
• Add a new metric to Inventory and Inventory alerts called 'CPU Usage' which uses the new definition

Note Do you think we could have a heading in there somewhere that talks about 'legacy' metrics that we can link to from the UI? We'd like to be able to refer to this from the UI

Resources

Related Issues:

• [Infra] Create new formula for CPU Usage metric kibana#188634
• Network metric calculations for the Host UI might be showing wrong values kibana#184099

Definitions:

"CPU Usage" (new)
"CPU Usage (legacy)"

"Network Inbound (RX)" (new)
"Network Inbound (RX) (Legacy)"

"Network Outbound (TX)" (new)
"Network Outbound (TX) (Legacy)"

Which documentation set does this change impact?

Stateful and Serverless

Feature differences

None

What release is this request related to?

8.16 (but sooner on serverless - TBC)

Collaboration model

The documentation team

Point of contact.

Main contact: @roshan-elastic

Stakeholders: @crespocarlos (coordinate with him on release dates)