[Transform] Reset plugin after tests (elastic#122252) (elastic#122423)

There is a race condition where the test is trying to clean up while the
Transform auditor is still writing messages - resetting the plugin will
stop the auditor (and properly reset it).

Fix elastic#12148

Author: prwhelan

x-pack/plugin/transform/src/internalClusterTest/java/org/elasticsearch/xpack/transform/checkpoint/TransformCCSCanMatchIT.java

@@ -12,6 +12,8 @@
 import org.apache.lucene.index.PointValues;
 import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.admin.cluster.snapshots.features.ResetFeatureStateAction;
+import org.elasticsearch.action.admin.cluster.snapshots.features.ResetFeatureStateRequest;
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.action.support.master.AcknowledgedResponse;
@@ -61,6 +63,7 @@
 import org.elasticsearch.xpack.core.transform.transforms.TransformStats;
 import org.elasticsearch.xpack.core.transform.transforms.latest.LatestConfig;
 import org.elasticsearch.xpack.transform.LocalStateTransform;
+import org.junit.After;
 import org.junit.Before;
 
 import java.io.IOException;
@@ -136,6 +139,11 @@ public void setUpNamedXContentRegistryAndIndices() throws Exception {
         remoteNewDocs = createIndexAndIndexDocs(REMOTE_CLUSTER, "remote_new_index", newRemoteNumShards, timestamp, randomBoolean());
     }
 
+    @After
+    public void cleanup() {
+        client().execute(ResetFeatureStateAction.INSTANCE, new ResetFeatureStateRequest(TEST_REQUEST_TIMEOUT)).actionGet();
+    }
+
     private int createIndexAndIndexDocs(String cluster, String index, int numberOfShards, long timestamp, boolean exposeTimestamp)
         throws Exception {
         Client client = client(cluster);