fix(server): move registering artifact metrics to after call response (#1828)

As commented in
#1824 (comment),
the status metrics is not obtained because we try to get it before
 the call happens.

This commit adjusts that by placing the metric increment to be after the
 call is processed.

Author: LeoColman

jit-binding-server/src/main/kotlin/io/github/typesafegithub/workflows/jitbindingserver/ArtifactRoutes.kt

@@ -56,13 +56,13 @@ private fun Route.headArtifact(
 
         val file = call.parameters["file"] ?: return@head call.respondNotFound()
 
-        incrementArtifactCounter(prometheusRegistry, call)
-
         if (file in bindingArtifacts) {
             call.respondText("Exists", status = HttpStatusCode.OK)
         } else {
             call.respondNotFound()
         }
+
+        incrementArtifactCounter(prometheusRegistry, call)
     }
 }
 
@@ -77,14 +77,14 @@ private fun Route.getArtifact(
 
         val file = call.parameters["file"] ?: return@get call.respondNotFound()
 
-        incrementArtifactCounter(prometheusRegistry, call)
-
         val artifact = bindingArtifacts[file] ?: return@get call.respondNotFound()
 
         when (artifact) {
             is TextArtifact -> call.respondText(artifact.data())
             is JarArtifact -> call.respondBytes(artifact.data(), ContentType.parse("application/java-archive"))
         }
+
+        incrementArtifactCounter(prometheusRegistry, call)
     }
 }