Enable APM tracing when --with-apm-server is used

[pgomulka]

when runtask (gradlew run) task is run with --with-apm-server apm tracing should also be enabled

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[elasticsearchmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[ldematte]

Seems quite straightforward, but I don't understand what is happening here. Can you elaborate?
This flag starts a mock APM server, so we also enable metrics, because it is convenient (we know there will be a mock server, so we can send metrics to it).
With this we are also enabling the agent; I suppose this was required too to complete the chain and was a miss, or is it something more?

[pgomulka]

Seems quite straightforward, but I don't understand what is happening here. Can you elaborate?
This flag starts a mock APM server, so we also enable metrics, because it is convenient (we know there will be a mock server, so we can send metrics to it).
With this we are also enabling the agent; I suppose this was required too to complete the chain and was a miss, or is it something more?

telemetry.metrics.enabled", "true is a flag to enable apm metrics (it was there before, not touched in this PR)
tracing.apm.agent.enabled", "true is a flag to enable apm tracing. The name is misleading I agree, we did not change this due to BWC. It was previously disabled (not missed)
those are separate feature that can work independently.

perhaps we should work at some point to cleanup the old settings names

[ldematte]

OK, so now when the mock server is enabled, we conveniently also enable both metrics and tracing (before it was metrics only). Unless they are explicitly set as disabled in the settings.
If so, LGTM

[pgomulka]

OK, so now when the mock server is enabled, we conveniently also enable both metrics and tracing (before it was metrics only). Unless they are explicitly set as disabled in the settings.

yes :)