Make hostmetricsreceiver available in otel mode

[ycombinator]

Describe the enhancement:

Include the hostmetricsreceiver in the OTel Collector components we bundle with Elastic Agent.

Describe a specific use case for the enhancement or feature:

Users of Elastic Agent in OTel mode (elastic-agent otel ...) would like to be able to use the hostmetricsreceiver in their OTel Collector pipeline configurations.

What is the definition of done?

• A test that runs Elastic Agent in OTel mode (elastic-agent otel ...) includes the hostmetricsreceiver in it's test OTel Collector configuration and the test passes.

[ycombinator]

Note that an attempt was already made to try and bundle the hostmetricsreceiver with Elastic Agent in #4706 but CI failed Serverless tests 🤷 on the following error:

>>> (windows-amd64-2022-fleet) Test output (sudo) (stdout): Error: error starting service: failed to start service (Elastic Agent): The service did not respond to the start or control request in a timely fashion.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[ycombinator]

Please remember to backport this issue's PR to the 8.14 branch.