Fix Couchbase 2.6 span assertions and plugin resolution

Couchbase 2.6 spans no longer emit the deprecated network.* span
attributes, so the 2.6 test subclasses should use the shared default that
expects them to be absent. The smoke-test build also needed Maven Central in
pluginManagement so Spring Boot plugin classpath dependencies are resolved
outside the Gradle Plugin Portal.

Validated with:
.\gradlew.bat :instrumentation:couchbase:couchbase-2.6:javaagent:test -PtestJavaVersion=8 -PtestJavaVM=hotspot -PtestIndy=true --no-daemon
.\gradlew.bat :smoke-tests:test -PsmokeTestSuite=none --no-daemon

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: trask

instrumentation/couchbase/couchbase-2.6/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/couchbase/v2_6/CouchbaseAsyncClient26Test.java

@@ -16,9 +16,4 @@ protected DefaultCouchbaseEnvironment.Builder envBuilder(
       BucketSettings bucketSettings, int carrierDirectPort, int httpDirectPort) {
     return Couchbase26Util.envBuilder(bucketSettings, carrierDirectPort, httpDirectPort);
   }
-
-  @Override
-  protected boolean includesNetworkAttributes() {
-    return true;
-  }
 }

instrumentation/couchbase/couchbase-2.6/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/couchbase/v2_6/CouchbaseClient26Test.java

@@ -27,11 +27,6 @@ protected DefaultCouchbaseEnvironment.Builder envBuilder(
     return Couchbase26Util.envBuilder(bucketSettings, carrierDirectPort, httpDirectPort);
   }
 
-  @Override
-  protected boolean includesNetworkAttributes() {
-    return true;
-  }
-
   @Test
   void hasDurationMetric() {
     CouchbaseCluster cluster = prepareCluster(bucketCouchbase);

instrumentation/couchbase/couchbase-2.6/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/couchbase/v2_6/springdata/CouchbaseSpringRepository26Test.java

@@ -20,11 +20,6 @@ protected DefaultCouchbaseEnvironment.Builder envBuilder(
     return Couchbase26Util.envBuilder(bucketSettings, carrierDirectPort, httpDirectPort);
   }
 
-  @Override
-  protected boolean includesNetworkAttributes() {
-    return true;
-  }
-
   @Override
   protected TestDocument findById(TestRepository repository, String id) {
     return repository.findById(id).get();

instrumentation/couchbase/couchbase-2.6/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/couchbase/v2_6/springdata/CouchbaseSpringTemplate26Test.java

@@ -17,9 +17,4 @@ protected DefaultCouchbaseEnvironment.Builder envBuilder(
       BucketSettings bucketSettings, int carrierDirectPort, int httpDirectPort) {
     return Couchbase26Util.envBuilder(bucketSettings, carrierDirectPort, httpDirectPort);
   }
-
-  @Override
-  protected boolean includesNetworkAttributes() {
-    return true;
-  }
 }

settings.gradle.kts

@@ -1,4 +1,9 @@
 pluginManagement {
+  repositories {
+    gradlePluginPortal()
+    mavenCentral()
+  }
+
   plugins {
     id("com.github.jk1.dependency-license-report") version "3.1.2"
     id("com.google.cloud.tools.jib") version "3.5.3"