Skip delete .plugins-ml-config system index during integ test

Signed-off-by: Junqiu Lei <junqiu@amazon.com>

Author: junqiu-lei

src/testFixtures/java/org/opensearch/knn/ODFERestTestCase.java

@@ -52,6 +52,7 @@
 import static org.opensearch.knn.TestUtils.KNN_BWC_PREFIX;
 import static org.opensearch.knn.TestUtils.OPENDISTRO_SECURITY;
 import static org.opensearch.knn.TestUtils.OPENSEARCH_SYSTEM_INDEX_PREFIX;
+import static org.opensearch.knn.TestUtils.PLUGINS_ML_CONFIG_INDEX_NAME;
 import static org.opensearch.knn.TestUtils.SECURITY_AUDITLOG_PREFIX;
 import static org.opensearch.knn.TestUtils.SKIP_DELETE_MODEL_INDEX;
 import static org.opensearch.knn.common.KNNConstants.MODELS;
@@ -212,6 +213,7 @@ private boolean skipDeleteIndex(String indexName) {
         return indexName == null
             || OPENDISTRO_SECURITY.equals(indexName)
             || IMMUTABLE_INDEX_PREFIXES.stream().anyMatch(indexName::startsWith)
-            || MODEL_INDEX_NAME.equals(indexName);
+            || MODEL_INDEX_NAME.equals(indexName)
+            || PLUGINS_ML_CONFIG_INDEX_NAME.equals(indexName);
     }
 }

src/testFixtures/java/org/opensearch/knn/TestUtils.java

@@ -99,6 +99,7 @@ public class TestUtils {
     public static final String UPGRADED_CLUSTER = "upgraded_cluster";
     public static final String SECURITY_AUDITLOG_PREFIX = "security-auditlog";
     public static final String OPENSEARCH_SYSTEM_INDEX_PREFIX = ".opensearch";
+    public static final String PLUGINS_ML_CONFIG_INDEX_NAME = ".plugins-ml-config";
 
     // Generating vectors using random function with a seed which makes these vectors standard and generate same vectors for each run.
     public static float[][] randomlyGenerateStandardVectors(int numVectors, int dimensions, int seed) {