Healthcheck service returning unhealthy between tests if service is reconfigured

[Dogacel]

This issue is mentioned as a comment here but probably unnoticed:

routeAdded, routeRemoved look useful for HealthCheckService also. At this moment, a newly reconfigured HealthCheckService doesn't work because the service depends on the server's start status:

https://github.com/line/armeria/blob/8ed438da36ba4e0f7d111c00f748b3fcc2906e2c/core/src/main/java/com/linecorp/armeria/server/healthcheck/HealthCheckService.java#L292-L297 And we should remove ServerListener when routeRemoved. It remains and wastes our memory (a little 😅).

Originally posted by @0x1306e6d in https://github.com/line/armeria/issues/3041#issuecomment-1322901060

Minimum reprod:

class STE : FunSpec({
    val server =
        object : ServerExtension(true) {
            override fun configure(sb: ServerBuilder) {
                sb.http(12345)
                    .service("/healthcheck", HealthCheckService.of())
            }
        }
    extensions(JUnitExtensionAdapter(server))

    test("is healthy") {
        val client = server.webClient()

        client.get("/healthcheck").aggregate().join().contentUtf8() shouldBe """{"healthy":true}"""

        server.server().reconfigure {
            it.service("/healthcheck", HealthCheckService.of())
        }

        client.get("/healthcheck").aggregate().join().contentUtf8() shouldBe """{"healthy":true}"""
    }
})

[seonWKim]

Maybe we can solve this issue in here or any following issues after it's solved. 🤔