[Fleet] Add fleet server telemetry

[nchaulet]

Summary

Resolve #95424
Add Fleet Server telemetry

While working on this I also added the number of updating agent to the agent collector.

New key added

"fleet" : {
  "fleet_server": {
        total_all_statuses: 3,
        total_enrolled: 3,
        healthy: 2,
        unhealthy: 1,
        offline: 0,
        updating: 0,
        num_host_urls: 2,
  }
}

Todo

• add tests

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[kpollich]

One super minor comment otherwise LGTM 🚀

[kpollich]

Does this need the [...policyIds]? .map won't mutate the array, so this could maybe be policyIds.map directly w/o the copy.

[nchaulet]

policyIds is not an array it's a set (I want uniq values) so I think we need the spread operator here.

[kpollich]

Ah I understand. Array.from might convey the intent more explicitly in that case: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 6cbd41e
• Storybooks Preview

Metrics [docs]

✅ unchanged

History

• 💚 Build #129938 succeeded 1b0c838
• 💚 Build #129599 succeeded a0dacdc
• 💚 Build #129483 succeeded aa73aa6
• 💔 Build #129224 failed 9be5d2c

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @nchaulet

[kibanamachine]

💚 Backport successful

Status	Branch	Result
✅	7.x

This backport PR will be merged automatically after passing CI.

[amolnater-qasource]

Hi @EricDavisX
We have created 02 testcases for this ticket under Ingest Manager Test Suite:

• C147375
• C147376

Thanks
QAS

[dikshachauhan-qasource]

Hi @EricDavisX

We have validated features on 7.14BC1 and found them working fine. Please find test cases execution under below mentioned test run.

• New Feature test run

Thanks
QAS