Fixes a usage of deprecated 'http.enabled' to the new 'api.enabled' (e…

…lastic#13380)

With elastic#13308 configuration namespace that started with `http.` was renamed to `api.`, this commit fix a usage left behind.
Use the new `api.enabled` setting in one place instead of the deprecated `http.enable`.

Co-authored-by: Ry Biesemeyer <yaauie@users.noreply.github.com>
(cherry picked from commit 88c80eb)

x-pack/lib/monitoring/inputs/metrics/stats_event_factory.rb

@@ -12,7 +12,7 @@ def initialize(global_stats, snapshot, cluster_uuid)
       @snapshot = snapshot
       @metric_store = @snapshot.metric_store
       @cluster_uuid = cluster_uuid
-      @webserver_enabled = LogStash::SETTINGS.get_value("http.enabled")
+      @webserver_enabled = LogStash::SETTINGS.get_value("api.enabled")
     end
 
     def make(agent, extended_performance_collection=true, collection_interval=10)

x-pack/spec/monitoring/inputs/metrics/stats_event_factory_spec.rb

@@ -17,7 +17,7 @@
     global_stats = {"uuid" => "00001" }
     sut = described_class.new(global_stats, collector.snapshot_metric, nil)
     LogStash::SETTINGS.set_value("monitoring.enabled", false)
-    LogStash::SETTINGS.set_value("api.http.enabled", webserver_enabled)
+    LogStash::SETTINGS.set_value("api.enabled", webserver_enabled)
 
     monitoring_evt = sut.make(agent, true)
     json = JSON.parse(monitoring_evt.to_json)