[Ingest Management] Use ECS metadata from elastic agent

[michalpristas]

Elastic agent now sends ECS compliant metadata introduced in this PR elastic/beats#17894

There's a need to replace use of these metadata from local_metadata

• platform
• version
• host

To ECS.

{
 "os" : { "platform": "windows" },
 "agent": {"version": "8.0.0"},
"host": {"hostname": "foobar"},
}

cc @nchaulet

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[ph]

@michalpristas This will need to be an object. ^

[nchaulet]

@ph @michalpristas are you sending data like this

{
"host.name": "host"
}

or

{
  "host": { "name": "host"}
}

[ph]

@nchaulet at the moment we are sending "host.name" but I believe it should be, this would align with ECS, are you proposing to convert it on your side?

{
  "host": { "name": "host"}
}

[michalpristas]

yes that's the plan, atm it is Key Value, once your change is in PR i will transform to objects