fix toString on operational metrics (#219)

Signed-off-by: Chenyang Ji <cyji@amazon.com>

Author: ansjcy

src/main/java/org/opensearch/plugin/insights/core/metrics/OperationalMetric.java

@@ -33,6 +33,6 @@ public String getDescription() {
 
     @Override
     public String toString() {
-        return String.format(Locale.ROOT, "%s (%s)", name(), description);
+        return String.format(Locale.ROOT, "%s", name());
     }
 }

src/test/java/org/opensearch/plugin/insights/core/metrics/OperationalMetricsTests.java

@@ -28,9 +28,14 @@ public void testEnumValues() {
 
     public void testToString() {
         // Test the toString method
-        assertEquals(
-            "LOCAL_INDEX_READER_PARSING_EXCEPTIONS (Number of errors when parsing with LocalIndexReader)",
-            OperationalMetric.LOCAL_INDEX_READER_PARSING_EXCEPTIONS.toString()
-        );
+        assertEquals("LOCAL_INDEX_READER_PARSING_EXCEPTIONS", OperationalMetric.LOCAL_INDEX_READER_PARSING_EXCEPTIONS.toString());
+        assertEquals("LOCAL_INDEX_EXPORTER_BULK_FAILURES", OperationalMetric.LOCAL_INDEX_EXPORTER_BULK_FAILURES.toString());
+        assertEquals("LOCAL_INDEX_EXPORTER_DELETE_FAILURES", OperationalMetric.LOCAL_INDEX_EXPORTER_DELETE_FAILURES.toString());
+        assertEquals("LOCAL_INDEX_EXPORTER_EXCEPTIONS", OperationalMetric.LOCAL_INDEX_EXPORTER_EXCEPTIONS.toString());
+        assertEquals("INVALID_EXPORTER_TYPE_FAILURES", OperationalMetric.INVALID_EXPORTER_TYPE_FAILURES.toString());
+        assertEquals("DATA_INGEST_EXCEPTIONS", OperationalMetric.DATA_INGEST_EXCEPTIONS.toString());
+        assertEquals("QUERY_CATEGORIZE_EXCEPTIONS", OperationalMetric.QUERY_CATEGORIZE_EXCEPTIONS.toString());
+        assertEquals("EXPORTER_FAIL_TO_CLOSE_EXCEPTION", OperationalMetric.EXPORTER_FAIL_TO_CLOSE_EXCEPTION.toString());
+        assertEquals("TOP_N_QUERIES_USAGE_COUNT", OperationalMetric.TOP_N_QUERIES_USAGE_COUNT.toString());
     }
 }