feat(metrics) Rename request context metric names to follow convention

Author: abedatahub

metadata-operation-context/src/main/java/io/datahubproject/metadata/context/RequestContext.java

@@ -275,11 +275,11 @@ private static void captureAPIMetrics(MetricUtils metricUtils, RequestContext re
       metricUtils.incrementMicrometer(
           MetricUtils.DATAHUB_REQUEST_COUNT,
           1,
-          "user.category",
+          "user_category",
           userCategory,
-          "agent.class",
+          "agent_class",
           agentClass,
-          "request.api",
+          "request_api",
           requestAPI);
     }
   }

metadata-utils/src/main/java/com/linkedin/metadata/utils/metrics/MetricUtils.java

@@ -21,10 +21,10 @@ public class MetricUtils {
   public static final String DROPWIZARD_METRIC = "dwizMetric";
   public static final String DROPWIZARD_NAME = "dwizName";
 
-  /* Micrometer */
+  /* Micrometer. See https://prometheus.io/docs/practices/naming/ */
   public static final String KAFKA_MESSAGE_QUEUE_TIME = "kafka.message.queue.time";
   public static final String DATAHUB_REQUEST_HOOK_QUEUE_TIME = "datahub.request.hook.queue.time";
-  public static final String DATAHUB_REQUEST_COUNT = "datahub.request.count";
+  public static final String DATAHUB_REQUEST_COUNT = "datahub_request_count";
 
   /* OpenTelemetry */
   public static final String CACHE_HIT_ATTR = "cache.hit";