chore: rename the metrics ITs test

Author: lqiu96

java-datastore/google-cloud-datastore/src/test/java/com/google/cloud/datastore/ITDatastoreBuiltInAndCustomMetrics.java

@@ -130,6 +130,7 @@ public void setUp() {
                 DatastoreOpenTelemetryOptions.newBuilder()
                     .setMetricsEnabled(true)
                     .setOpenTelemetry(customOtel)
+                    .setExportBuiltinMetricsToGoogleCloudMonitoring(true)
                     .build())
             .build();
     datastore = options.getService();