chore(samples): Add samples for Cloud Spanner Default Backup Schedules.

Adding `s` to create instance sample class name

Author: Sally-Ye

samples/snippets/src/main/java/com/example/spanner/CreateInstanceWithoutDefaultBackupScheduleExample.java renamed to samples/snippets/src/main/java/com/example/spanner/CreateInstanceWithoutDefaultBackupSchedulesExample.java

@@ -27,16 +27,16 @@
 import com.google.spanner.admin.instance.v1.ProjectName;
 import java.util.concurrent.ExecutionException;
 
-class CreateInstanceWithoutDefaultBackupScheduleExample {
+class CreateInstanceWithoutDefaultBackupSchedulesExample {
 
-  static void createInstanceWithoutDefaultBackupSchedule() {
+  static void createInstanceWithoutDefaultBackupSchedules() {
     // TODO(developer): Replace these variables before running the sample.
     String projectId = "my-project";
     String instanceId = "my-instance";
-    createInstanceWithoutDefaultBackupSchedule(projectId, instanceId);
+    createInstanceWithoutDefaultBackupSchedules(projectId, instanceId);
   }
 
-  static void createInstanceWithoutDefaultBackupSchedule(String projectId, String instanceId) {
+  static void createInstanceWithoutDefaultBackupSchedules(String projectId, String instanceId) {
     // Set Instance configuration.
     int nodeCount = 2;
     String displayName = "Descriptive name";

samples/snippets/src/test/java/com/example/spanner/SpannerSampleIT.java

@@ -702,8 +702,8 @@ public void testCreateAndUpdateInstanceDefaultBackupScheduleTypeSample() {
         runSampleRunnable(
             () -> {
               try {
-                CreateInstanceWithoutDefaultBackupScheduleExample
-                    .createInstanceWithoutDefaultBackupSchedule(
+                CreateInstanceWithoutDefaultBackupSchedulesExample
+                    .createInstanceWithoutDefaultBackupSchedules(
                         dbId.getInstanceId().getProject(), instanceId);
                 UpdateInstanceDefaultBackupScheduleTypeExample
                     .updateInstanceDefaultBackupScheduleType(