4.x: Move archetype metrics under GreetService

[tvallin]

Description

fix #7611

Removed the MetricsService and moved the metrics logic to GreetService

Documentation

no impact

[tjquinno]

I see that the generated test assertions now check only for the presence of the expected metrics and not the values. It would be nice if there was a way to verify the value as well, as we did before. I know it can be tedious to get the output, parse the output and save the current value, then access an endpoint, then retrieve the output and parse it again, and finally make sure the change in value is correct (rather than the absolute value) but would that work?

[tvallin]

Yes that would work. Other possibility is to use ordered test method and run metric test first so we can avoid parsing metrics endpoint output for SE. Would you like this approach ?

[tjquinno]

Mostly looks good, but I am reluctant to approve the PR because there will be more changes to how the archetype should generate the SE code once Tomas finishes some current work.

Also, ideally we would avoid depending on test ordering among the test methods. If Romain is OK with it then I will be as well.

[tvallin]

That's okay, I just removed the ordered test and parse the metrics instead to get the values.

[tjquinno]

1. You have probably already seen the conflict now in observerability.xml.

2. I cloned your repo and switched to your refactor-archetype and rebuilt Helidon and the archetypes.

   When I run helidon init using the local cli-data the dialog for a custom SE project prompts for a metrics provider (Microprofile or Micrometer). If the user asks for metrics in the custom SE dialog, the pom should not ask further metrics-related questions (similar to the recent change to the 3.x archetype).

   A generated SE project with metrics support should include these metrics-related dependencies:

        <dependency>
            <groupId>io.helidon.webserver.observe</groupId>
            <artifactId>helidon-webserver-observe-metrics</artifactId>
        </dependency>
        <dependency>
            <groupId>io.helidon.metrics</groupId>
            <artifactId>helidon-metrics-system-meters</artifactId>
            <scope>runtime</scope>
        </dependency>

   This might be a change from when we first talked about what metrics dependencies should be in 4.x SE projects. For now, at least, we have decided not to use the helidon-metrics bundle in our SE metrics examples.