[Test] Use default project s3 repo tests

The stateful side tests generally do not exercise multi-project.
Therefore we need to use the default project-id instead of random one.

Relates: #127631

Author: ywangd

modules/repository-s3/src/test/java/org/elasticsearch/repositories/s3/S3RepositoryTests.java

@@ -165,9 +165,8 @@ public void testEmptyBucketName() {
     }
 
     private S3Repository createS3Repo(RepositoryMetadata metadata) {
-        final ProjectId projectId = randomProjectIdOrDefault();
         final S3Repository s3Repository = new S3Repository(
-            projectId,
+            ProjectId.DEFAULT,
             metadata,
             NamedXContentRegistry.EMPTY,
             new DummyS3Service(
@@ -181,7 +180,7 @@ private S3Repository createS3Repo(RepositoryMetadata metadata) {
             new RecoverySettings(Settings.EMPTY, new ClusterSettings(Settings.EMPTY, ClusterSettings.BUILT_IN_CLUSTER_SETTINGS)),
             S3RepositoriesMetrics.NOOP
         );
-        assertThat(s3Repository.getProjectId(), equalTo(projectId));
+        assertThat(s3Repository.getProjectId(), equalTo(ProjectId.DEFAULT));
         return s3Repository;
     }