Prometheus: alarm-related metric naming

(cherry picked from commit 47b20e8)

Author: michaelklishin

deps/rabbitmq_prometheus/src/collectors/prometheus_rabbitmq_alarm_metrics_collector.erl

@@ -51,12 +51,12 @@ collect_mf(_Registry, Callback) ->
                                    [untyped_metric(maps:get(file_descriptor_limit,
                                                             ActiveAlarms,
                                                             0))])),
-                Callback(create_mf(?METRIC_NAME(<<"disk_limit">>),
-                                   <<"is 1 if disk alarm is in effect">>,
+                Callback(create_mf(?METRIC_NAME(<<"free_disk_space_watermark">>),
+                                   <<"is 1 if free disk space watermark alarm is in effect">>,
                                    untyped,
                                    [untyped_metric(maps:get(disk_limit, ActiveAlarms, 0))])),
-                Callback(create_mf(?METRIC_NAME(<<"memory_limit">>),
-                                   <<"is 1 if memory alarm is in effect">>,
+                Callback(create_mf(?METRIC_NAME(<<"memory_used_watermark">>),
+                                   <<"is 1 if VM memory watermark alarm is in effect">>,
                                    untyped,
                                    [untyped_metric(maps:get(memory_limit, ActiveAlarms, 0))])),
                 ok;