System tests for OTel policies must check that the default policy template name matches with the expected receiver

[jsoriano]

Follow up to elastic/kibana#237145.

Default dataset for OTel inputs should be the same that would be used by the vanilla OTel collector with the community receiver.

This helps to integrate with content packages developed for the community receivers. For example the MySQL content package expects documents to contain mysqlreceiver.otel dataset (see here). So a possible mysql input package should have mysqlreceiver as policy template name:

...
policy_templates:
  - name: mysqlreceiver # <- This name is used as default dataset in input packages.
    input: otelcol
    ...

Add a check to ensure that this name, and by this, the default dataset, corresponds to the one of the receiver.

Future integration packages for OTel will also need to take this into account (https://github.com/elastic/ingest-dev/issues/5713).

[jsoriano]

Not sure how to test this.
A naive way would be to look for the receiver name in the agent config template, and ensure that the policy template name matches. Even if naive, this would work if all community receivers respect this convention.
A more complex and accurate option would be to run the agent with the configuration for the receiver but without the routing attributes, or adding a transform to delete them.