Reduce flakiness in io.opentelemetry.javaagent.instrumentation.couchbase.v2_6.CouchbaseClient26Test.upsertAndGet(BucketSettings)[2]

Automated fix attempt based on Develocity flaky-test analysis.

Author: trask

instrumentation/couchbase/couchbase-common/testing/src/main/java/io/opentelemetry/instrumentation/couchbase/AbstractCouchbaseClientTest.java

@@ -61,6 +61,8 @@ private static Stream<Arguments> bucketSettings() {
   protected CouchbaseCluster prepareCluster(BucketSettings bucketSettings) {
     CouchbaseEnvironment environment = envBuilder(bucketSettings).build();
     CouchbaseCluster cluster = CouchbaseCluster.create(environment, singletonList("127.0.0.1"));
+    // AutoCleanupExtension runs in LIFO order; clear spans emitted while closing the client.
+    cleanup.deferCleanup(testing::clearData);
     cleanup.deferCleanup(environment::shutdown);
     cleanup.deferCleanup(cluster::disconnect);